From maximizing efficiency in a jet engine’s turbine to ensuring the reliable, vibration-free operation of a simple industrial pump, the rotating component is where performance and reliability are won or lost.

What is rotating equipment?

Simply put, rotating equipment is any machinery that relies on rotational motion to perform its function. Unlike static equipment (like pipes or storage tanks), these devices are designed to convert energy into mechanical motion, often for moving fluids or generating power.

Common examples span a wide range of industries:

• Pumps (Centrifugal, Axial)
• Turbines (Gas, Steam, Wind)
• Compressors (Centrifugal, Axial)
• Fans and Blowers
• Motors and Generators
• Propellers and Impellers

What is the difference between static and rotating equipment?

The main difference between static and rotating equipment is movement.

• Static equipment (like pipes, tanks, or heat exchangers) is stationary and has no moving parts.
• Rotating equipment (like pumps, turbines, or motors) uses spinning components to actively create motion or generate power.

Rotating equipment types in depth

Let’s have a look at the different types of rotating equipment in a bit more depth.

Pumps (Centrifugal, Axial)

Pumps stand as the workhorses of industry, hydraulic machines designed to transport fluids by converting rotational kinetic energy into hydrodynamic energy. The most common types, centrifugal pumps, use a rotating impeller to fling fluid outwards, while axial pumps use a propeller-style mechanism to move fluid along the shaft’s axis. From water supply systems to chemical processing, their applications are endless. But how can one optimize their performance and prevent damaging issues like cavitation? This is where modern engineering simulation steps in, allowing engineers to digitally visualize flow patterns and pressure zones to achieve design excellence before a physical prototype is ever built.

Turbines (Gas, Steam, Wind)

Turbines are critical in our pursuit of energy, acting as sophisticated engines that extract energy from a fluid flow and convert it into useful rotational work, most often to power a generator. Whether it’s a gas turbine using hot combustion gases, a steam turbine driven by high-pressure steam, or a wind turbine capturing the kinetic energy of the air, their core principle is to harness natural forces. The design of their complex blades is paramount to performance. Cloud-native simulation platforms offer a robust framework for modeling these intricate fluid-structure interactions, helping engineers optimize blade geometry to maximize efficiency and reliability.

Compressors (Centrifugal, Axial)

Compressors are vital machines whose primary function is to increase the pressure of a gas by reducing its volume. Like pumps, they are commonly found in centrifugal (radial) and axial flow configurations, each suited for different pressure ratios and flow rates. These devices are the heart of everything from jet engines and industrial refrigeration to gas pipeline transport. Achieving high efficiency and a stable operating range is a key design challenge. Using computational fluid dynamics (CFD), engineers can meticulously simulate the high-speed, complex flow through blade passages to optimize designs and minimize energy losses.

Fans and Blowers

While often grouped with compressors, fans and blowers are specifically designed to move large volumes of air or gas, typically at a much lower pressure differential. Their function is essential for ventilation in buildings (HVAC), cooling electronics, or supplying combustion air in industrial furnaces. The main challenge in their design is to achieve the required flow rate while minimizing power consumption and acoustic noise. Engineering simulation plays a key role here, allowing designers to analyze airflow, test blade profiles, and visualize turbulence to create quieter and more efficient systems.

Motors and Generators

These two devices are the cornerstone of our electrified world, managing the conversion between mechanical and electrical energy. A motor takes electrical energy and converts it into mechanical rotation to drive a pump, fan, or compressor. A generator does the exact opposite, taking rotational energy from a turbine and converting it into electrical energy for the grid. Optimizing their design requires a deep understanding of electromagnetics and thermal management. Multiphysics simulation is crucial, enabling engineers to analyze magnetic fields, predict heat buildup, and ensure the structural integrity of these fundamental machines.

Propellers and Impellers

At the very heart of nearly all turbomachinery, you will find a rotating component designed to interact with a fluid: the propeller or the impeller. An impeller, such as one in a centrifugal pump, is designed to transfer energy to the fluid, increasing its velocity and pressure. A propeller, used for propulsion or in a turbine, interacts with the fluid to create thrust or extract work. The specific geometry of these components—their blade curvature, angle, and number—is the single most critical factor in the machine’s overall performance. Their design is a perfect use case for simulation, which allows for detailed flow analysis to maximize efficiency and minimize wear.

Rotating equipment in our public projects

Here is a range of rotating equipment that has been simulated with SimScale by our community.

Rotating equipment challenges

The continuous operation of rotating equipment is fundamental to global infrastructure, from power generation to manufacturing. Efficiency and reliability failures carry a massive cost. For instance, even a one percent drop in efficiency across a fleet of industrial pumps or compressors translates into millions of dollars in wasted energy annually. Any component failure driven by vibration or fatigue can trigger unscheduled downtime, which instantly halts production or utility service.

Beyond these operational costs, the industry is now facing unprecedented pressure driven by global Net-Zero targets and evolving sustainability mandates. This shift requires nothing less than a revolution in design, pushing engineers to develop machines that achieve record-breaking efficiencies while incorporating new low-carbon technologies, such as advanced compressors for hydrogen or lighter, more powerful electric motors. Therefore, optimizing these machines isn’t merely about achieving peak performance; it is a business-critical requirement for safeguarding financial viability and ensuring operational continuity in a sustainable future.

Some examples of government mandated Minimum Energy Performance Standards (MEPS) are given below.

Simulating rotating equipment with SimScale

Engineering simulation provides the vital advantage needed to tackle the complex challenges of rotating equipment proactively. By modeling real-world physics in a virtual environment, designers can rapidly explore changes and predict performance before a prototype is ever built, leading to significant cost reduction, increased reliability and lifespan, and accelerated time to market.

At SimScale, we are committed to providing accessible, high-performance simulation tools right in your web browser. For rotating equipment, our platform offers a powerful, validated suite of simulation types across fluid dynamics, structural mechanics, and electromagnetics.

Computational Fluid Dynamics (CFD)

To master the fluid flow within your turbomachinery, SimScale’s online CFD simulation capabilities offer two primary approaches. For initial design exploration and quickly mapping basic performance curves (like pump curves), the Multiple Reference Frame (MRF) method provides a computationally fast, steady-state approximation. However, for maximum fidelity in predicting complex phenomena—such as rotor-stator interactions, pressure pulsations, or cavitation—the Transient Analysis utilizing the highly accurate Sliding Mesh technique is essential. Furthermore, you can accelerate your entire development cycle by using Parametric Studies to automatically run dozens of variations (different speeds, flow rates, geometries) in parallel, efficiently generating a full performance map.

Read how Hazleton Pumps generated performance curves 100x faster with SimScale.

Finite Element Analysis (FEA)

Structural integrity and vibration avoidance are paramount for rotating equipment reliability. SimScale’s FEA tools focus on guaranteeing these factors. By conducting Rotational Modal Analysis, engineers can compute natural frequencies while accounting for rotational effects (centrifugal forces), which is crucial for identifying and avoiding critical speeds that lead to destructive resonance. The results are used to generate Campbell Diagrams for definitive vibration diagnosis. For detailed assessment, Harmonic and Transient Analysis allows designers to predict dynamic stresses resulting from forces like unbalance, ensuring the component’s fatigue life is sufficient.

Learn more about Rotational Modal Analysis and Campbell Diagrams on the SimScale Blog.

Electromagnetic (EM) Simulations

Electric motors and generators are a critical subset of rotating equipment, and their efficiency is governed by electromagnetics. SimScale’s EM solvers accurately calculate crucial machine characteristics like magnetic fields, flux, and torque output, which is necessary for meeting strict IE4/IE5 efficiency standards. To capture real-world performance accurately, these results can be integrated into Multiphysics Coupling workflows, linking electrical losses (heat) to a thermal analysis, which then feeds into a structural analysis to assess the impact of temperature on material stresses

Learn more about Multiphysics Simulation in SimScale.

Why SimScale for Your Rotating Equipment Design?

SimScale’s commitment to the rotating machinery sector is all about making advanced physics accessible. Our cloud-native platform is specifically engineered to overcome the common barriers of traditional CAE:

1. Speed and Parallelism: Run complex transient and parametric studies in parallel, reducing the turnaround time from days to hours.
2. Accessibility: No heavy software installation or specialized hardware is needed. Access powerful HPC from your web browser, anywhere.
3. Ease of Use: An intuitive interface and validated workflows, including specialized rotating machinery meshing, allow design engineers to conduct simulations without needing deep simulation expertise.

By leveraging SimScale, your team can Simulate Early, Simulate More, and Simulate Now—leading to faster design cycles, highly optimized products that meet global efficiency mandates, and maximum operational reliability for all your rotating equipment.

FAQs

The post What is Rotating Equipment? appeared first on SimScale.

In this article, we will discuss the details of impeller design, its challenges, and their solutions. We will also examine how engineering simulation, especially cloud-native simulation, enables engineers to create more efficient and reliable impellers.

Basic Principles of Impeller Design

Impeller design uses fundamental fluid dynamics and energy transfer principles to function effectively. The primary function of an impeller is to convert mechanical energy from a motor into kinetic energy in the fluid. This process is governed by several fundamental principles and equations.

Bernoulli’s Equation

One of the foundational equations in fluid dynamics is Bernoulli’s equation, which describes energy conservation in a flowing fluid. It states that the total mechanical energy of the fluid remains constant along a streamline. The equation is given by:

$$ P = \frac{1}{2}\rho v^2 + \rho gh = constant $$

where

• \(P\) is the static pressure.
• \(\rho\) is the fluid density.
• \(v\) is the fluid velocity.
• \(g\) is the acceleration due to gravity.
• \(h\) is the height above a reference point.

Euler’s Turbomachinery Equation

Another critical principle is Euler’s turbomachinery equation, which relates the change in fluid energy to the impeller’s geometry and rotational speed. It is given by:

$$ \Delta H = \frac{U_2 V_{u2} – U_1 V_{u1}}{g} $$

where

• \(\Delta H\) is the head increase imparted to the fluid.
• \(U\) is the tangential velocity of the impeller.
• \(V_u\) is the tangential component of the absolute velocity of the fluid at the inlet (1) and outlet (2) of the impeller.
• \(g\) is the acceleration due to gravity.

This equation is essential for determining the work done by the impeller on the fluid and is used to calculate the pressure increase provided by the impeller.

Key Design Parameters

The design of the impeller itself involves several key geometric parameters that influence its performance. These include:

• Impeller Diameter: The impeller diameter impacts both the head and flow rate. Larger diameters increase head and flow but also raise energy consumption. The relationship is approximated by the affinity law: \(H \propto D^2\)
• Blade Angle: Blade angles at the inlet (\(\beta_1)\) and outlet (\(\beta_2)\) are crucial for smooth fluid entry and exit, minimizing flow separation and turbulence. Optimized angles enhance energy transfer efficiency.
• Number of Blades: More blades reduce fluid slip and improve efficiency but increase manufacturing complexity. The optimal number balances efficiency and practical considerations.
• Blade Shape and Curvature: Curved blades guide fluid better than straight ones, reducing turbulence and energy losses. The blade shape is tailored to specific applications, such as radial, mixed-flow, or axial-flow impellers.
• Impeller Width: Impeller width affects flow rate and efficiency. Wider impellers handle larger flow rates but may increase friction losses. Narrower impellers are more efficient but support lower flow rates.
• Material Selection: Material choice impacts durability and resistance to wear and corrosion. Common materials include stainless steel, cast iron, and various alloys, selected based on operating conditions.
• Surface Finish: A smooth surface finish on blades and shrouds reduces friction and turbulence, enhancing hydraulic efficiency. Precision casting and surface coatings can improve the surface finish.

Types of Impellers

Table 1 below shows the types of impellers used in turbomachinery equipment (pumps or turbines).

Role of Engineering Simulation in Impeller Design

Simulating and evaluating a pump impeller early in the design process is crucial for determining the optimal design. However, traditional on-premises simulation tools are often costly and have steep learning curves.

Cloud-native simulation solutions offer significant advantages over traditional on-premises simulations. They provide scalable computing power, enabling engineers to run large-scale and complex simulations without local hardware limitations. Tools like SimScale eliminate these barriers by leveraging the power of the cloud.

Engineers can benefit from a seamless workflow of CAD modeling and simulation using SimScale and CFturbo. This workflow enables faster turbomachinery modeling in the cloud by allowing engineers to seamlessly create CAD models of rotating machinery, such as impellers, in CFturbo and simulate them in SimScale to evaluate their blade profiles, pressure-flow characteristics, and efficiency requirements.

With scalable, high-performance computing and a binary tree-based mesher that allow for high-fidelity meshing and simulation, engineers can leverage the CFturbo-SimScale combined workflow to achieve fast simulation time, parallel simulation capabilities, stable simulation convergence, and high simulation accuracy—all in their favorite web browser; no hardware limitations and no installations are required.

With SimScale, engineers can:

• Optimize impeller designs faster by running several simulations simultaneously
• Use FEA and thermal analysis to test the stress and strain applied to pump impellers
• Get started quickly on an easy-to-use interface without extensive training
• Access cost-effective solutions and faster processing times

Cloud-Native Simulation for Industrial Machinery Manufacturing

Our latest eBook explores how cloud-native simulation is transforming industrial machinery manufacturing challenges into opportunities. Download it for free by clicking the button below.

Download eBook

Solving Cavitation Problems in Pumps

Cavitation is the formation of vapor bubbles inside a liquid with low pressure and high flow velocity. It is the leading cause of performance deterioration in pumps and turbines, significantly affecting impellers.

SimScale offers advanced simulation tools that allow engineers to model and analyze cavitation effects in pumps and turbomachinery. Using SimScale, engineers can:

• Conduct Comprehensive Analyses: Utilize computational fluid dynamics (CFD), structural (FEA), and thermal analyses through automated workflows and intuitive interfaces.
• Model Cavitation Phenomena: Understand the impact of cavitation on performance by simulating cavitating flow and studying parameters like the net positive suction head required (NPSHR), cavitation number, and inlet sizing.
• Optimize Pump Efficiency: Use the Multi-purpose CFD solver to study and optimize pressure drop, fluid flow patterns, and cavitation effects. The solver’s robust meshing strategy ensures high-quality meshes and faster simulations.
• Import and Edit CAD Models: Easily import CAD models from various software and perform essential operations like flow volume extraction and defining rotating zones.
• Visualize Results: Leverage advanced visualization tools to analyze flow behavior, pressure distribution, velocity vectors, and cavitation effects.

Optimize Impeller Design With SimScale Cloud-Native Simulation

Are you seeking faster innovation and higher impeller design efficiency? SimScale offers a robust solution for reducing the time and cost associated with design and prototyping while maximizing accuracy and enhancing decision-making.

For engineers and designers aiming to push the boundaries of impeller design, SimScale provides the flexibility to explore innovative turbomachinery modeling. With SimScale’s integration with CFturbo, users can boost their impeller design modeling, benefiting from a seamless workflow that allows for faster and more accurate design and simulations.

SimScale’s advanced simulation capabilities enable you to test and validate innovative concepts that might be impractical or too risky to prototype traditionally. Experience the power of cloud-native simulation with SimScale. Sign up below and start simulating today.

Contributors: Muhammad Faizan Khan, Samir Jaber

The post Impeller Design: Types, Applications, and Simulation appeared first on SimScale.

Pelton turbines are characterized by their distinctive spoon-shaped buckets that efficiently capture the momentum of high-velocity water jets in high-head hydroelectric projects. But what differentiates the Pelton turbine in the spectrum of hydroelectric technologies? And how are current technological advancements, particularly cloud-based simulation platforms, revolutionizing the design, optimization, and operational processes of Pelton turbines?

This article delves into the intricacies of Pelton turbines, tracing their origins, understanding their mechanics, and exploring the role of advanced computation simulations, such as those offered by SimScale, in enhancing their performance.

Understanding Pelton Turbines

What is a Pelton Turbine?

A Pelton turbine, also known as a Pelton wheel turbine, is an impulse turbine uniquely designed to convert the kinetic energy of water into mechanical energy. Unlike its counterparts – the Francis and Kaplan turbines, which are reaction turbines suited for lower-head and higher-flow applications – the Pelton turbine operates efficiently in high-head, low-flow conditions typical of mountainous terrains. It achieves this by directing high-velocity water jets at a series of buckets mounted around the wheel, known as the runner, capturing the water’s momentum with remarkable efficiency.

Historical Background and Modern Applications

Invented in 1880 by Lester A. Pelton, the Pelton turbine has become a cornerstone of modern hydropower technology [1]. With the global installed capacity of hydropower reaching 1330 GW in 2021 and expected to grow significantly by 2050, Pelton turbines are at the forefront of this expansion [2]. They are renowned for their high efficiency, which can reach up to 92%, and continue to be refined for even greater performance.

In modern applications, Pelton turbines are not just confined to large-scale hydropower plants. They are also instrumental in small-scale installations, particularly in remote and mountainous regions where their high-head, low-flow operation is optimal. Furthermore, they are increasingly integrated into smart grid systems, contributing to a more responsive and sustainable electricity network. Pelton turbines also play a pivotal role in managing environmental flows, ensuring that water usage for power generation balances ecological and human needs.

Key Components of a Pelton Turbine

• The Bucket Design: The buckets of a Pelton turbine are its defining feature. They are engineered to split the water jet, ensuring maximum energy transfer from water to the turbine and allowing for efficiencies to remain high, even when operating at part load.
• The Nozzle: The nozzle, or injector, is responsible for regulating the water flow rate. It is designed to maintain high efficiency across a range of operating conditions, ideally keeping Pelton turbine efficiency above 90% until the flow rate is reduced to 20% of the design flow rate [3].
• The Runner and Casing: The runner, with its mounted buckets, is enclosed within a casing to protect and streamline the operation. The turbine’s axis configuration, whether horizontal (with up to two injectors) or vertical (with as many as six injectors), affects the load distribution and efficiency. The design also includes a deflector for emergency shutdowns or to prevent damage.

Pelton turbines are adaptable to horizontal and vertical axis configurations, with the choice impacting the turbine’s load distribution and potential for energy loss due to friction and windage. Their ability to operate efficiently across a wide range of conditions makes them a versatile choice for hydropower installations, especially in areas with high heads and low flows, such as aqueducts or ecological flows from dams.

How Pelton Turbines Work?

Pelton turbines derive their efficiency from the basic principle of impulse, where pressurized water is directed through a penstock and expelled via a carefully sized nozzle to generate a high-speed water jet. The turbine wheel, featuring strategically positioned double-cupped buckets, efficiently captures and redirects this water jet. Upon impact, the water undergoes a rapid change in momentum, transferring its kinetic energy to the turbine wheel and inducing rotation. The rotating turbine wheel is connected to a generator, converting the mechanical energy into electrical power. This synchronized process ensures continuous and reliable power generation.

The hydraulic efficiency of a Pelton wheel turbine is typically calculated using the following formula:

$$ Hydraulic\:Ef\!ficiency = \left(\frac{Mechanical\:Power\:Out\!put}{Hydraulic\:Power\:In\!put}\right) × 100 $$
It is also referred to as the Power Coefficient and is expressed as follows:
$$ \eta = \frac{P_t}{P_w} $$

where \(\eta\) is the hydraulic efficiency, \(P_t\) is the turbine power output, and \(P_w\) is the water head (unconstrained water current).

This formula quantifies the efficiency of the turbine in converting the hydraulic power of the incoming water into mechanical power. The mechanical power output is the electrical power generated by the turbine, while the hydraulic power input is the energy carried by the water jet.

Pelton turbines, with their distinctive design and efficient water-to-wheel energy transfer, often yield hydraulic efficiencies in the range of 85% to 90%. This means that a significant proportion of the water’s kinetic energy is successfully harnessed to produce electrical power. Yet, this efficiency may drop or fluctuate depending on influencing factors, such as windage, mechanical friction, backsplashing, and nonuniform bucket flow.

Advancements in Pelton Turbine Design Through Simulation

The integration of engineering simulation technologies, notably Computational Fluid Dynamics (CFD), has transformed the design and analysis of Pelton turbines. This innovative approach allows for the detailed modeling of water flow dynamics within the turbine, providing engineers with the insights needed to enhance efficiency and precision in turbine designs. As we delve deeper into the specifics, we will explore how Pelton turbine simulation serves as a crucial foundation for design refinement, performance prediction, and, ultimately, the realization of more sophisticated and efficient Pelton turbine systems.

Engineering simulations are pivotal during the early stages of the design cycle of Pelton turbines, acting as virtual proving grounds. They enable the testing of various design concepts, material choices, and operational conditions without the need for physical prototyping. This stage is essential for pinpointing potential design flaws and implementing improvements, thereby conserving time and resources.

Optimizing Pelton Turbine Designs with CFD

CFD simulations offer a robust framework for tackling fluid flow challenges, allowing for the creation of three-dimensional models of Pelton turbines. These models provide a window into the intricate interactions between water jets and turbine buckets, facilitating the optimization of bucket design, nozzle placement, and runner shape to achieve high turbine efficiency.

This is where a simulation tool like SimScale CFD plays a key role. Not only does this tool provide accurate simulation capabilities, but it also offers parallelization by leveraging cloud computing and storage. In other words, multiple simulations can run in parallel without limitations imposed by hardware constraints. This saves significant time during the design process and enables design parameterization and efficient testing. More on this is discussed below.

Dynamic Visualization and Performance Forecasting in Pelton Turbine Simulation

A key benefit of CFD simulations is the dynamic visualization of water flow through the turbine blades, offering more than just static imagery. Engineers can track the formation and impact of water jets on the buckets, observing the resulting flow paths. This dynamic analysis is crucial for identifying and rectifying inefficiencies. Furthermore, simulations enable turbine performance prediction across a spectrum of conditions, allowing engineers to anticipate real-world functionality and ensure the most efficient and dependable operation of a Pelton turbine.

Cloud-Native Simulation for Industrial Machinery Manufacturing

Our latest eBook explores how cloud-native simulation is transforming industrial machinery manufacturing challenges into opportunities. Download it for free by clicking the button below.

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Cloud-Native CFD to Accelerate Pelton Turbine Innovation

SimScale’s Multi-purpose Analysis for CFD Simulation of Pelton Turbines

In Simscale, the most useful CFD analysis type to simulate Pelton turbines is Multi-purpose Analysis. The Multi-purpose analysis type introduces an automated and robust meshing strategy tailored for fluid flow applications like Pelton Turbines. This approach generates hexahedral cells optimized for the underlying solver, significantly reducing mesh generation times. The resultant high-quality mesh requires fewer cells to achieve comparable accuracy, leading to faster convergence. It is important to note that this efficiency may come with a reduction in the feature set.

Key features of the mesher include body-fitted Cartesian meshing, cells suitable for finite volume discretization, and a highly parallelized meshing algorithm for rapid processing.

The Multi-purpose solver in SimScale is a Finite Volume-based CFD solver, employing a segregated pressure-velocity coupling mechanism. It stands out for its ability to simulate both incompressible and compressible flows, accommodating laminar or turbulent conditions all in one place. It also offers versatility by supporting both steady-state and extensive transient analyses. As for turbulence modeling, the analysis relies on the Reynolds-Averaged Navier-Stokes (RANS) equations, employing the k-epsilon turbulence model for closure and proprietary wall functions for effective near-wall treatment, making it particularly suited for Pelton Turbines.

Enhancing Pelton Turbine Design with SimScale’s Predictive Analysis

SimScale’s simulation capabilities bring a new level of sophistication to the design and optimization of Pelton turbines. Across numerous projects hosted on the platform, SimScale users are harnessing the power of cloud-native CFD simulation to enhance the operational efficiency and reliability of these turbines.

One such project studied the water flow within a Pelton turbine, mapping velocity magnitudes throughout the turbine’s buckets. This analysis provided a detailed visualization of flow dynamics, enabling the identification of optimal flow conditions and guiding improvements to the turbine design for increased energy conversion efficiency.

In another study, the focus was placed on understanding the pressure distribution within the turbine. The simulations executed in SimScale offered a three-dimensional perspective on the pressure loads the turbine blades endure, which is fundamental for assessing the turbine’s structural integrity and ensuring its longevity under high-stress conditions.

Through these projects, SimScale has proven to be an invaluable tool for predictive analysis that is vital for the refinement of turbine designs. It enables engineers to virtually prototype and test their concepts, iterate designs with accuracy, and achieve a level of detail that significantly reduces the need for physical prototypes. Try it for yourself now by clicking on “Start Simulating” below. For more information about SimScale’s CFD tool, check out our Fluid Dynamics product page.

The post Pelton Turbine: Working Principle, Design & Simulation appeared first on SimScale.

But what makes them tick? How do they transform a simple rotation into the steady flow that powers humans’ daily lives? And how can one simulate and analyze their performance to achieve design excellence?

This is where SimScale Turbomachinery CFD steps in, your ultimate solution for simulating centrifugal pumps and calculating their operational efficiency.

What is a Centrifugal Pump?

A centrifugal pump is a hydraulic machine designed to transport fluids by converting rotational kinetic energy from an external source (e.g., an electric motor) into hydrodynamic energy. This transformation makes it possible for fluids to move from one place to another with impressive efficiency and scale.

Before engineering simulation tools like SimScale, engineers relied heavily on manual calculations and physical tests. Optimizing designs meant repeated physical testing, which was both time-consuming and tedious. Today, with cloud-native engineering simulation software, engineers can visualize flow patterns, pressure zones, and potential areas of cavitation within the digital environment. If inefficiencies are detected, modifications can be made instantly to the digital model and re-simulated.

How Does a Centrifugal Pump Work?

Key Components of a centrifugal pump

The main components of a centrifugal pump are:

• Impeller: The spinning part with curved blades. Fluid enters through its center, called the ‘eye,’ and exits by being pushed out through the blades.
• Casing: The housing that surrounds the impeller. Two main types of casings exist – volute and diffuser.
  • Volute casings have a curved shape, helping increase fluid pressure as the fluid flows.
  • Diffuser casings use stationary blades to increase fluid pressure.
• Shaft: Connects the impeller to the motor, allowing the impeller to spin.

In addition, centrifugal pumps also require shaft sealings (mechanical seals or packing rings) to prevent fluid leakage, a shaft sleeve to protect the shaft and position the impeller-shaft combo precisely, and bearings to minimize friction between the rotating shaft and the stator.

These parts can be divided into the pump’s wet end and mechanical end.

• The wet end components are responsible for the pump’s hydraulic performance; these are the impeller and the casing. In some designs, the first radial bearing can also belong to the wet end, where it is water-filled.
• The mechanical end components support the impeller within the casing; these are the shaft, shaft sleeve, sealing, and bearings.

Working Principle of Centrifugal Pump

When the electric motor turns the shaft, the impeller starts spinning (typically rotating at speeds ranging from 500-5000 rpm). This draws fluid into the pump. The spinning impeller pushes the fluid outwards.

The design of the casing then guides this fluid (either volute or diffuser), increasing its speed and pressure. The fluid exits the pump, typically from an outlet at the top of the casing.

Pump Comparison: Centrifugal vs Positive Displacement

Pumps are used to move fluids in different settings. Generally, the two main types of pumps are positive displacement pumps and centrifugal pumps. Positive displacement pumps keep a constant flow rate, whereas centrifugal pumps’ flow rate varies based on the fluid pressure. The choice of pump largely depends on the pump’s working principle, fluid viscosity, and application.

Positive displacement pumps are suitable for high-viscosity fluids and are used in food processing, oil refining, and pharmaceuticals. Centrifugal pumps, on the other hand, are suitable for low-viscosity fluids and are used in water treatment, irrigation, and heating/cooling systems.

The following table provides a direct comparison between centrifugal pumps and positive displacement pumps in terms of their operating principle, fluid type, flow rate, and more.

Types of Centrifugal Pump

Centrifugal pumps are a subset of dynamic axisymmetric turbomachinery. There are different types of centrifugal pumps that can be categorized based on specific criteria, such as impeller types, design codes, and applications. Here is a brief overview of the three main types of centrifugal pumps: radial pumps, axial pumps, and mixed pumps.

1. Radial Pumps

In radial pumps, fluid flows radially outward from the impeller’s center, perpendicular to the main axis. This type of centrifugal pump is used in cases where flow is restricted, and the goal is to increase the discharge pressure. Therefore, radial pump design is ideal for applications that require a high-pressure and low-flow rate pump, such as water supply, irrigation, and industrial processes.

2. Axial Pumps

Axial pumps work by moving the fluid in a parallel direction to the axis of the impeller. The operation of axial pumps is akin to that of propellers. Their most notable usage comes into play when there is a large flow rate and relatively low-pressure head required, such as fire pumps and large-scale irrigation systems.

3. Mixed Pumps

Mixed pumps combine the features of radial and axial pumps. They are capable of delivering high flow rates and pressures, making them ideal for applications such as sewage treatment and power generation.

Radial Pump vs Axial Pump vs Mixed Pump

Here is a table that summarizes the key differences between the three types of centrifugal pumps.

Single-Stage, Two-Stage, or Multi-Stage Centrifugal Pumps

Another way of classifying centrifugal pumps is by the number of impellers they have (or the number of stages), and they can be referred to as single-stage, two-stage, and multi-stage centrifugal pumps. A single-stage pump has one impeller, a two-stage pump has two impellers, and a multi-stage pump has three or more impellers.

• Single-stage pumps are the simplest and most common type of centrifugal pump. They are well-suited for applications where medium flow rates and pressures are required.
• Two-stage pumps are more efficient than single-stage pumps at delivering high pressures. They are often used in applications such as firefighting and industrial processes.
• Multi-stage pumps are the most efficient type of centrifugal pump, but they are also the most expensive. They are used in applications where very high pressures are required, such as oil and gas production and chemical processing.

Applications of Centrifugal Pump

Centrifugal pumps are used in a wide range of applications that involve turbomachinery, including:

• Water Supply: Whether it’s pumping water to homes, industrial plants, or agricultural fields, centrifugal pumps ensure a steady water flow.
• General Industrial Processes: Since many manufacturing processes rely on the consistent movement of fluids, centrifugal pumps help in transferring chemicals. For example, in a petrochemical plant or circulating coolant in machinery.
• Cooling Systems: In HVAC (Heating, Ventilation, and Air Conditioning) systems, centrifugal pumps circulate coolant to maintain temperature balance.
• Sewerage: Centrifugal pumps remove unwanted water, especially in areas prone to flooding or in construction sites.
• Oil and Energy Sector: In oil refineries and power plants, centrifugal pumps transport crude oil and hot liquids.
• Food & Beverage Industry: Safe and consistent transfer of liquids, like juices, syrups, and dairy products, is crucial. Centrifugal pumps offer a contamination-free and efficient solution.
• Wastewater Treatment: For processing and recycling wastewater, these pumps facilitate the movement of water through various stages of treatment.

Advantages of Centrifugal Pump

Centrifugal pumps offer advantages that can be quite useful in a variety of settings and applications:

1. Corrosion Resistance

Many fluids can rapidly corrode pumps, but corrosion-resistant centrifugal pumps can manage different fluids without deteriorating, thanks to the corrosion-resistant properties of their materials. Businesses see an increased return on investment (ROI) as the pumps last longer and require fewer replacements, maintenance, or repairs.

2. High Energy- and Cost-Efficiency

Centrifugal pumps use less power to move liquids, making them cost-effective. Any mechanical engineer would appreciate the savings they offer in terms of energy costs and efficiency gains.

3. Straightforward Design

When you look at a centrifugal pump, you see simplicity in action. These pumps don’t have countless parts, making them easier to produce, set up, and look after. In the long run, their design can lead to fewer repairs and a longer life.

Given their design simplicity and established principles of operation, engineers can use computational fluid dynamics (CFD) and other simulation tools to model their behavior under different conditions.

4. Stable Flow

For processes that need a steady liquid supply, centrifugal pumps are the go-to. They deliver a continuous flow, making sure everything runs as it should. This predictability can be crucial, especially when consistency is key to quality control in production lines.

5. Compact Design

Centrifugal pumps, with their compact form, are a perfect solution. They can fit adequately into tight spots, making them a smart choice for workshops and factories where every inch counts.

Disadvantages of Centrifugal Pump

While their advantages can prove effective in industrial applications, centrifugal pumps also have some drawbacks:

1. Inefficiency with High-Viscosity Feeds

Centrifugal pumps are best suited for liquids that have a viscosity range between 0.1 and 200 cP. With high-viscosity fluids like mud or slurry, their performance drops because they need to overcome greater resistance, and maintaining the desired flow rate demands higher pressure.

2. Priming Required Before Use

Centrifugal pumps can’t just start up on their own when they’re dry; they need to be primed or filled with the liquid first. This limitation means they might not be ideal for applications with intermittent liquid supply.

3. Susceptibility to Cavitation and Vibrations

Cavitation occurs when vapor bubbles form in the liquid being pumped due to sudden pressure changes, and then collapse when they reach areas of higher pressure. This phenomenon can lead to intense shock waves that damage the pump’s impeller and casing. The aftermath of cavitation is often visible as pitting or erosion on the impeller and the casing.

Cloud-Native Simulation for Industrial Machinery Manufacturing

Our latest eBook explores how cloud-native simulation is transforming industrial machinery manufacturing challenges into opportunities. Download it for free by clicking the button below.

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Centrifugal Pump Simulation With SimScale

By utilizing Turbomachinery CFD in SimScale, engineers can analyze their centrifugal pump’s performance and efficiency and identify areas of improvement in the design to ensure optimal operation. This analysis and design optimization can be further accelerated thanks to SimScale’s cloud-native nature, which enables engineers to run multiple simulations in parallel directly on their web browser without having to worry about any hardware limitations or installation complexities. They can also collaborate with team members and customer support in real time by simply sharing the link to their simulation project. As a result, engineers are empowered to innovate faster and optimize their pump designs more efficiently using SimScale’s powerful CFD solvers.

Here’s how SimScale helps the mechanical industry in centrifugal pump simulation:

1. Robust Meshing

SimScale’s Multi-purpose CFD solver provides a robust meshing strategy, generating an automated body-fitted mesh which is crucial for capturing the fluid flow accurately within and around the pump geometry.

2. Flow Analysis

SimScale allows for the analysis of various flow regimes including incompressible, compressible, laminar, and turbulent flows. This is essential in understanding how the fluid will behave under different operating conditions.

3. Cavitation Simulation

Cavitation, a common challenge in centrifugal pumps, can be simulated to understand its impact on pump performance. SimScale’s Multi-purpose multiphase CFD solver computes the space occupied by each phase, providing insights into cavitation effects in pumps.

4. Pump Curve Generation

SimScale enables engineers to generate pump curves within a few hours, whereas other simulation tools can take up to a few days. This is crucial for ensuring the pump meets the desired performance criteria across a range of operating conditions.

5. Transient Analysis

The platform supports full transient analysis, modeling fluid flow in a time-accurate manner, which is vital for capturing the dynamic behavior of the pump under various operational scenarios.

Simulate Your Centrifugal Pump Design in SimScale

Centrifugal pumps have revolutionized industries with their efficiency, compact design, and ability to move fluids at varying rates and pressures. While centrifugal pumps come with their set of challenges, advancements in engineering simulation and CFD tools like SimScale have enabled engineers to optimize designs and predict performance.

Sign up below and start simulating now, or request a demo from one of our experts. You may also follow one of our step-by-step tutorials, such as the advanced tutorial on Fluid Flow Simulation Through a Centrifugal Pump, or check out the following on-demand webinars:

• Get Ahead of the Pump Curve: Simulation-driven KSB Circulator Pump Optimization using CAESES (On-demand webinar)
• Parametric Studies for Rotating Machinery: Hands-On Workshop with SimScale (On-demand webinar)

The post Centrifugal Pump: Design, Working Principle, & Simulation appeared first on SimScale.

A heat circulator pump is a centrifugal pump designed to circulate heated fluids in closed systems like boilers, hot water pumping, etc., or open systems like swimming pools. Such pumps are subjected to high-temperature fluids and low-pressure heads in the circulating region, relative to the system pressure. Some common applications where heat circulator pumps are employed include underfloor heating systems, boilers and hot water circulators in buildings, ventilation, air conditioners, heat recovery systems, industrial recovery systems, etc. 

If not designed efficiently, heat circulator pumps can be the biggest energy drains in a heating or cooling system. The EU has placed stringent requirements on the design of circulator pumps, in-line with the aspiration to transition to a low-carbon economy by 2050. The “Energy-related Products (ErP)” directive of 2009 established an ecodesign framework for the design and operation of many ErP products including heat circulator pumps. Under this directive, manufacturers are required to comply with the prescribed energy and resource efficiency standards in order for their products to be sold in the EU.

The efficiency of heat circulator pumps is rated based on their ‘Energy Efficiency Index (EEI)’. EEI is a measure of how much the power input of the pump is lower than the prescribed power input. For example, an EEI of 0.21 means that the pump only utilizes 21% of the threshold power input. Thus, the lower the EEI value, the better the efficiency rating of the circulator pump. KSB, a world leader in pump and valve simulation & manufacturing, has a range of high-efficiency products like the Calio (EEI ≤ 0.2) and Calio Z (EEI ≤ 0.23). Read on to learn how KSB continues to innovate on the ecodesign of heat circulator pumps by using a simulation-driven approach in SimScale.

KSB Heat Circulator Pump Design and Optimization: Project Objectives

EEI is governed by the average power consumption across the load profile, compared to the reference hydraulic power. Typically, power consumption at 4 weighted flow rates, as shown in the hydraulic curve below, is used to evaluate the EEI. The weighted flow rate, Q_100%, is taken as the flow rate where (Q x H) is maximum and that is extrapolated to get the weighted flow rates Q_75%, Q_50%, and Q_25%, and the corresponding Power ‘P’ at those flow rates. 

Using the control curve shown in green, the weighted average electrical input power is calculated (Eq. 1) and is then used to compute the EEI of the specified circulator (Eq. 2).

Eq. (1) P_el,avg = 0.06 x P_L,100% + 0.15 x P_L,75% + 0.35 x P_L,50% + 0.44 x P_L,25%   

Eq. (2) EEI = (P_el,avg / P_hyd,ref) x C                            

where: 

P_hyd,ref = reference power

C = calibration factor ~ 0.49

Currently, the pump rarely ever operates at the best efficiency point. Motor power is usually limited which shifts the Q_100% to the left, resulting in a new control curve (dashed green line in figure 1). This means that the final EEI is now dependent on the motor as well as other systems components, most of which get finalized only in the final stage of the production process. 

This is the precise problem that the turbomachinery expert at KSB Germany, Toni Klemm, was faced with. How does one quickly select an impeller design, subject to specific EEI requirements, at the last stage of the production cycle? Does one leave the impeller design until late in the production process, risking a longer time to market as well as higher prototyping costs?

SimScale, in partnership with Friendship Systems AG, the makers of CAD design and shape optimization software CAESES, provided a cost-effective, simulation-driven approach to solve KSB’s problem. A hydraulic toolchain was developed to create a surrogate model of the pump impeller, which can be queried to select the right design based on the system requirements before production. 

Overview of SimScale – CAESES Workflow

CAESES is a powerful CAD modeling and shape optimization software, which can be integrated with any simulation-driven optimization loop. Its dependency-based modeling approach is fully automated and it comes with inbuilt strategies for flexible parametric design and shape optimization. 

SimScale’s turbomachinery solver combines best-in-class CFD techniques with cloud computing to accelerate simulation-driven design and analysis of pumps and turbomachinery. The solver accuracy is close to 2% in comparison to test data and a designer can calculate an entire pump curve, by simultaneously running multiple simulations in the cloud, in 15 minutes. This is possible using input parameterization for fast design prototyping and CAD associativity for easy geometry variation. A simple application programming interface (API) enables the integration of the turbomachinery solver with third-party optimization and design of experiment (DoE) tools. 

In this case study, the parametric CAD geometry of the heat pump impeller was generated in CAESES, which was connected with SimScale via the API for running a DoE to evaluate the parametric hydraulic performance curves. The CFD-driven performance characteristics for different designs were fed back to CAESES for surrogate model creation and optimization. 

The CAESES – SimScale workflow can be summarized as:

DoE in SimScale: Simulation Setup and Results

14 design variables were chosen for CAD parameterization in CAESES. These include:

Number of blades

Meridional contours (3 parameters)

Blade angle distributions 
• 2 parameters for LE and TE blade angles
• 2 parameters for the hub to shroud variation of LE blade angle
• 6 parameters for shape control of beta functions between LE and TE

For each design variant, 3 flow rates needed to be run (0.7, 0.85, 1.1 x Q/Q opt). A simple python script enabled the transfer of Parasolid CAD geometry and simulation inputs from CAESES to SimScale’s turbomachinery solver, where geometry meshing and simulations were run. The CFD simulations assumed incompressible, steady state, fully turbulent flow across the pump impeller, and further input condition parameterization was employed to run all three flow rates per geometry variant together. This enables automatic calculation of the performance curve including the pressure head across the impeller, shaft power, and efficiency, which are sent back to CAESES. The flow around the impeller for changing the blade exit angle and the corresponding performance curves are shown in Figure 2.

A massive DoE comprising 377 design variants (900+ simulations in total) was run in parallel in SimScale to evaluate the hydraulic performance of each variant and send it back to CAESES. The DoE statistics are given below:

Surrogate Model Creation and Optimization in CAESES

The DoE results from SimScale include 9 output parameters (head, efficiency, and power for 3 flow rates) as shown in Figure 3. Using these, surrogate models were created in CAESES by leveraging the inbuilt RSMtools feature and response surfaces for each of them can be visualized.

Next Steps

Optimizations on the surrogate models for minimal EEI are being planned. This needs measured performance curves for the full pump configuration, which will be approximated from the impeller-only DoE results. Testing of the surrogate models is also in progress, where the average power consumption at the weighted flow rates now computed should lead to lower EEI.

Faster Innovation With Simulation-Driven Design in SimScale

Using cloud-native simulation in SimScale accelerates product innovation by opening up a vast design space that is otherwise not possible due to cost and time constraints. In this case study, we saw how KSB company combined the DoE results from SimScale with optimization strategies in CAESES to develop a novel methodology for the rapid selection of circulator pump impellers while adhering to EU’s ecodesign regulations. A turnaround of 1.5 days for a DoE of 300+ designs at a compute cost of $300 is the perfect motivation for companies to embed cloud-native simulations in their product development cycles, from conceptual design all the way to production.

Be sure to watch the on-demand webinar to hear the full story on heat circulator pump optimization from Toni Klemm (KSB) and Mattia Brenner (Friendship Systems AG).

The post Design and Optimization of KSB Heat Circulator Pump Using SimScale and CAESES appeared first on SimScale.

From a simulation perspective, steady-state methods like frozen rotor and mixing planes do not capture the true transient nature of such flows and are therefore less accurate in predicting the turbomachine’s performance, especially in off-design conditions. A full transient analysis that models the actual movement of the rotor and its interaction with stationary components becomes necessary in such situations. 

Despite the limitations of steady-state methods, engineers and designers still heavily rely on them, either reserving transient analysis only for final stage prototyping when it may be difficult to make design changes, or completely skipping it. This trend is primarily driven by the disproportionately high computational requirements, long turnaround times, and workflow nuances of 3D transient simulations in traditional CAE tools. A transient run for a single data point could typically take a few days on a desktop workstation.

To bridge this gap, SimScale has developed cloud-native transient capabilities within its proprietary solver for rotating machinery, which yields converged results for a single data point as well as a parametric sweep in under 4 hours. Our technology employs the sliding mesh technique in a robust binary-tree mesher and high-order accurate RANS solver, which can handle incompressible as well as compressible flow. In this article, we present how the newest addition to our rotating equipment simulation technology paves the way for fast and accurate transient analysis early in the design stages of digital prototyping.

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Fast and Accurate 

As the pioneer of cloud-native simulation, SimScale continues to perfect its cloud computing algorithms that make it possible to run transient simulations in a fraction of the time taken by traditional CAE. For example, a full transient simulation for a centrifugal pump on a mesh size of nearly 0.6 million cells takes under 20 minutes to complete. The same simulation in traditional CAE tools would take at least 12 hours or even a couple of days. Combined with the parametric studies capability that we launched in 2021, it is also now possible to obtain performance curves with the full transient physics included in nearly the same time as a single data point run.

To establish the accuracy and reliability of the transient solution, we have validated the solver against a range of standard benchmark cases. Figure B below shows the comparison of power vs. flow rate for a centrifugal pump. The results from the transient analysis are a very good match with the experiment, closer than the steady-state MRF method. Mesh independence study for this case led to a mesh size of about 0.6 million cells and a full transient run for one flow rate took 18 minutes to complete. 

Intuitive and Accessible 

In traditional CFD software, getting the correct mesh arrangement across the sliding interface, and consequently, quality results from a transient analysis requires a high level of CFD expertise. Additionally, complex simulation workflows often frustrate designers and engineers, forcing them to devote more time to navigating software nuances than on iterating and perfecting their designs. SimScale is committed to breaking down the technical and economical barriers to advanced simulation. Our proprietary CFD technology for rotating machinery is built on the foundations of accessibility and ease of use, with the aim of enabling faster design iterations in a cost-effective manner. With the introduction of the advanced transient analysis capability, we continue to focus on features that allow greater automation and ease-of-use, including: 

• Robust binary tree mesher that automatically generates optimal mesh interfaces between the rotating and stationary components
• Workflow parity between steady-state and transient analysis —using the transient approach is as simple as turning on a switch
• Real time visualization of results in the built-in post-processor
• Intuitive user interface with physics-based, predefined inputs
• Browser-based simulation that can be accessed, and collaboratively worked on, from anywhere in the world

Advanced Transient Analysis for Rotating Equipment

With the addition of the transient analysis capability in SimScale, it is now possible to include comprehensive physics in rotating equipment CFD and predict their effect on the component’s performance and wear and tear. Cloud-native implementation means that transient simulations in SimScale are orders of magnitude faster than in on-premise software. 

Whether you are a pump engineer interested in analyzing vibrations due to flow pulsations, or a turbine designer optimizing the blade to reduce flow separation, cloud-native transient analysis capability offers you the advantage of super-fast design iterations, early in the design process and throughout the product’s life cycle. With SimScale, advanced transient analysis that was previously computationally expensive, time-consuming, or required expertise is now accessible via a browser, in a cloud-native platform that is scalable, easy to use, and cost-effective.

Learn more in our whitepaper: Simulating Turbomachinery Designs 10x Faster

Download Whitepaper

The post Cloud-Native Transient Analysis for Rotating Equipment appeared first on SimScale.

• How do we extract the last iota of efficiency from a pump or a turbine? 
• How do we optimize the operation and maintenance of critical rotating equipment without increasing costs? 
• How do we reduce time to market and stay ahead of the competition?

The answer is SimScale’s newest offering for rotating equipment simulations, which harnesses the power of the cloud to enable phenomenally fast and accurate simulations for flow and performance assessment of rotating equipment.

Fast and Accurate Simulation of Rotating Equipment

Consider the performance study of a centrifugal pump, which involves calculating the pump’s pressure head and efficiency for a range of outlet flow rates to generate what is known as the ‘pump curve’. Typically, a pump curve requires a minimum of six input data points and can take from days to months to produce in traditional software.

Our customer Benjamin van der Walt, from Hazleton Pumps, agrees. He says, “We averaged about 3-6 days to simulate 1 data point with AMI (transient simulation) and 9-15 hours with MRF (steady-state) on HPC. Generating a pump curve, with ideally 6 data points, can take up to a month”. With SimScale’s new proprietary rotating machinery technology, it is now possible to generate a pump curve for a medium-sized geometry within 15 minutes (See Figure 1).

The highly parallelized and cloud-optimized algorithms that form the backbone of our new technology enable users to make design decisions faster by running parametric studies at the same time as a single data point run.  

Solution accuracy is critical to the design and analysis of rotating equipment and cannot be compromised at any cost. Cognizant of this fact, we have tested and validated our proprietary technology for a variety of academic and industrial use cases to obtain solution accuracy within 1-5% of experimental data.

Figure (2) depicts the pump curve parametric sweep, which includes a mesh independence study, and the results obtained from SimScale are within a 2% error of experiment. The solver is backed by high-fidelity numerical models and robust mesh generation techniques that can handle a variety of flow physics through different types of rotating equipment.  

Accessible and Versatile Simulation

In rotating machinery simulations, it is common for traditional simulation tools to have turnaround times that run into days and also require a sizable investment in scalable hardware and data management processes. In most cases, the inherent complexity of rotating machinery simulation workflows can be quite frustrating for designers and engineers, resulting in a further increase in project lead times.

SimScale’s cloud-native simulation technology for rotating machinery not only reduces the simulation turnaround time to minutes but also drives the IT and hardware costs of companies to zero. We have invested heavily in automating and simplifying the simulation workflow so that rotating machinery designers and engineers do not get bogged down with the nuances of local software licensing and can instead devote their time to analyzing, iterating, and improving their designs.

Users can access the browser-based platform from anywhere in the world through a simple login, run multiple simulations simultaneously, and collaborate with team members on any projects they wish to share.

Cloud-Native Simulation for Rotating Equipment

SimScale is committed to making fast and accurate simulation accessible to all engineers working with rotating equipment and facilitating its adoption across applications and throughout the product’s lifecycle. We are confident that our proprietary technology for rotating machinery will help companies make significant savings in money and time, which they can channel back into doing what they do best – building better products faster.

Webinar: Pump Design Powered by the Cloud with Hazleton Pumps

Watch our on-demand webinar to see how simple it is to set up a simulation using our new technology for rotating machinery and get performance pump curves for all types of rotating equipment accurately and in minutes, not days:

Watch On-Demand Webinar

The post Rotating Equipment Design Powered by the Cloud appeared first on SimScale.

Matter: Matter is defined as a physical structure that has mass and volume in space. It comprises all forms of physical elements that exist in the form of atoms. Uranium, water, salt, and even a piece of wood, are all expressed as matter.

Phase: It is a distinctive form of matter with three types:

• Solid: Shape and volume are definite
• Liquid: Volume is definite, yet the shape belongs to the container
• Gas: Shape and volume belong to the entire structure of the container

Interface: In a system with different phases, a narrow and distinct region, known as the ‘phase interface’, emerges. The phases on either side of the interface have different chemical and physical properties, and mathematical expressions are required to model the transport of mass, momentum, and energy across the interface.

Some examples of multiphase flows include a mixture of liquid mercury and liquid water and phase-changing processes like the transition of ice into liquid water. The expression of multiphase fluid flow might be indicated as “number of phases” + “flow” in accordance with the total number of phases. For instance, the mixture of liquid water and liquid oil can be classed as a two-phase flow or a multiphase flow. On the upshot, multiphase flow is the interaction of more than one matter or phase of matter that exists simultaneously. Transportation of mass, momentum, and energy among phases—based on conservation laws—is examined through the simulation.

Multiphase Flow Models

For the purpose of carrying out a reliable numerical simulation, the mathematical model which describes the physics should be scrutinized. For instance, transition among phases such as condensation, requires an appropriate mathematical model, correlation, or theory which defines the condensation process as accurately as possible.

Generally, the modeling process of multiphase flow includes three main stages, which are the description of the physical process, the specification of the flow, and the determination of the suitable mathematical model.

Description of the Physical Process

In the case that fluid flow comprises more than one phase, the physical model should be defined properly to describe the governing process so as to herald fluid flow and even mathematical model. Some of the processes and models might be specified concerning multiphase flow, as illustrated in Figure 2.

Specification of the Fluid Flow Regime

There are various types of multiphase fluid flow in the literature that diversify in accordance with the physical process and properties of the problem, and these can be classified into three main fields:

Separated Phases: More than one immiscible fluid in continuous phases and separated by interface [1].

Mixed Phases: Presence of both separated and dispersed phases [2].

Dispersed Phases: Finite numbers of phases spread through the volume of continuous phases such as droplets, drops, particles, or bubbles [1].

Various types of fluid flow can be classified, as shown in Figure 3:

The Mathematical Model

The discrimination of phases in the numerical simulation relies on the rate of volume or mass. To determine an appropriate mathematical model for fluid flow, factors such as physical process and flow regime have to be described in advance. Several mathematical models have been developed in order to properly simulate fluid flow. The investigation of multiphase flow still has several hindrances due to complexities related to the mathematical models. However, the Navier-Stokes equations might be broadly used to examine multiphase flows, and the capability of hardware in conducting numerical studies, which are reliant on Navier-Stokes equations, is still far from an affirmative solution.

Over and above that, a challenging model—such as those related to turbulence, chemical reaction, or mass transfer—carries the problem to a further level of complexity. For this reason, generating both realistic and simpler models is the key factor for multiphase fluid flow simulations [1]. The most commonly used mathematical approaches—such as empirical correlations—might be conducted as follows [3]:

• Volume of Fluid (VOF): Separated flows, free surface flows
• Lagrangian Multiphase (LMP): Droplet flows, track individual point particles, particles do not interact
• Discrete Element Method (DEM): Particle flows, solve the trajectories of individual objects and their collisions, inside a continuous phase
• Eulerian Multiphase (EMO): Dispersed flow, particle flows, bubbly flows, boiling heat and mass transfers, interphase mass transfer
• Eulerian/Lagrangian Dispersed Phase Model (DPM): Particle-wall interaction is always considered, particle-particle is usually not
• Eulerian-Eulerian Model (EEM): Particle-wall interaction is considered, particle-particle is usually not
• Eulerian-Granular Model (EGM): Both particle-wall and particle-particle interaction are considered

Apart from the models above, further miscellaneous models can be found in the literature according to the type of fluid flow.

Application of Multiphase Flow

Many engineering problems depend on the numerical examination of fluid flow, which typically comprises more than one phase. Automotive, power generation, chemical industry, food industry, environment, and even medicine are some sectors that have been using numerical tools to predict the outcomes in advance. To learn more about multiphase simulation within SimScale, check out the latest features in this on-demand webinar.

The post Multiphase Flow in CFD: Basics and Modeling appeared first on SimScale.