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Better Valve Design and increased ROI with Simulation

Valves design - SimScale

Associated with the consumer needs of water, gas or other utility agent flow control, the most important applications of the valves are industrial, mainly associated with mining, oil and gas extraction, processing and distribution, water circulation, power generation, chemical, manufacturing or food processing.

Why are Valves so Important?

The valves industry requires continuous design and manufacturing process improvement. The industrial revolution driven by digital technologies is claiming not only innovative products, but also better processes, product customization, fastest access to market, cost reduction and general efficiency improvement by fast return on investment (ROI).

Modern manufacturing processes are based on the same digital model of a valve, used in all fabrication workflows, from engineering concept and design to testing laboratories and engineering validation, production, marketing and sales. The global demand for industrial valves is projected to grow with 5.4% average rate in the next 5 years, for a market value expected to surpass $70 billion by 2019. The increasing demand in oil & gas, chemical and utility applications is expected to be the major drivers for the industrial valves market development. [1]

The valves industry is one of the verticals where engineering and design should be in close relationship. The market’s needs of innovative formats and functionalities has influenced the creation of dedicated CAE/Computer-aided engineering or CAD/Computer-aided design specialised solutions that enable design improvements based on real-time simulation iterations.

A classical manufacturing process could take a few weeks to create a new valve model. Using engineering simulation, the time needed for the same model can be dramatically shortened, sometimes even to 1 day.

Any optimization process should be based on a complex set of analyses, including structural, dynamic flow, thermal behavior or acoustics. Each of this simulation methods and the cumulative modelling result are generating valuable valve design functionalities, replacing or reducing physical testing and associated costs.

The key reasons simulation is widely used today in the valve industry are:
• Interactive models could forecast next changes in design layout, being vital for improving valves performance
• Simulation models offer precise and detailed information about valves design parameters, material structure and thermal comportment
• Valves simulation saves cost and time, eliminating the needs for physical prototypes

Due to the large applicability, the valves simulation models are used in many vertical industries for different analytical capabilities such as aerospace, automotive, HVAC, petrochemicals, power generation, manufacturing, oil and gas process engineering, or turbomachinery.

Different Models of Valves and Suggested Simulations

The essential purposes of valves simulation is related to functionalities and format, performance optimization and behavior of some standard models. Here is a summary of the main valves models and the functional particularities to be considered in the design process:

Globe valve – mainly used for regulation flow, comes with main advantages of a balancing feature which reduces the required actuator forces. CFD/Computational fluid dynamics and structural analyses mainly recommended;
Butterfly valve – based on a rotating vane, it is a high-pressure recovery valve used in applications where high-capacity, fast velocity and relative high pressure are required; Starting from this, a powerful combination between CFD/Computational fluid dynamics and structural analysis is recommended;
Ball valve – the ball control based on a rotating system, being a high-pressure recovery type of valve, in which the flow of fluid is restricted by using a full or partial type ball in the valve body. A powerful combination between solid standard FEA and CFD/Computational fluid dynamics analysis is recommended.
Gate valve – regularly designed for high pressure and temperature motive fluids. Structural, CFD/Computational fluid dynamics and Thermal analyses recommended.
Diaphragm valve – controls flow by a movement of a diaphragm. Upstream pressure, downstream pressure, or an external pneumatic or hydraulic source can be used to change the position of the diaphragm. Pressure analyse for diaphragm and CFD/Computational fluid dynamics are recommended.
Flow Control Valves (FCV) – used in many applications involving high pressure and fuel control, such as spatial transportation vehicles, request critical structural, CFD/Computational fluid dynamics, thermal and acoustic analyses.
Three-way valve – primarily used for splitting or mixing service. The most common applications are related to heat transfer control or in the controlled mixing of two streams. Recommended analyses: structural, CFD/Computational fluid dynamics, thermal;
Thermal expansion valve – used in refrigeration and air conditioning systems. CFD/Computational fluid dynamics and thermal analyses recommended.

Structural Analysis for Valves

Regardless of the applicability and model type, the valves are generally designed for high temperature and fluids that could impact the structural strength of the valves, due to excessive stress generation and concentration in restrictive regions. The most confident way to establish a reliable structural behavior for a valve is to perform a stress analyse based on the finite element method (FEM).

A stress analysis investigates first of all the stress state of valve body, considering various loading conditions. Main analyses are focused on the body material nonlinearity considering elastic-plastic behavior. The valves connections with different pipeline or recipient interfaces should be considered.

CFD Simulation for Valves Optimization

Based on numerical methods to solve the fundamental nonlinear differential equations that describe fluid flow for predefined geometries and boundary conditions, CFD software facilitates valves structure optimization in design of hydraulic components.

The CFD simulation process suggests a range of models for flow velocity, density, low-pressure zones around the corners, impingement angles for wear studies, minimum temperature behavior or chemical concentrations for any region where flow occurs.

Continuous improvement in CFD mathematical models and the increase in speed and capacity of workstations made possible the implementation of newest CFD modelling, producing simulations for full 3D flow dynamics.

Thermal Analysis of Valves

For many industries where the valves are controlling the high temperature of the fluids, there is a possibility of the valve components to deform under such high thermal stresses and develop cracks in the assembly, leading the valve to fail prematurely.

Especially the high-temperature valves [2] are designed to deal with the effects of thermal expansion and the loss of body material strength at elevated temperatures. In many cases some high-temperature valves must also deal with the issue of thermal shock. The rate at which any valve component heats up is dependent on the local heat transfer coefficient and on the local temperature difference between component and the steam.

The main simulation variables are related to local steam velocity across the component surface and the thermal boundary layer. Valves thermal simulation is based on common method using finite element analysis (FEA) to conduct a transient thermal analysis.

Valves Acoustic Analysis

Related to valve geometry and pressure behavior, the acoustics prediction are very important in many valve design applications. Acoustic waves are analysed as compression waves generated in a compressible medium at the speed of sound of the particular medium.

If the full turbulent time varying pressure field can be understood, then it is possible to calculate the noise generated. Having properly computing resources, the sound pressure level produced by a valve trim could be calculated. [2]

Why Valve Design and Optimization with SimScale?

The most important advantage for using SimScale in valve design optimization is the user has the same web-based environment for any type or for multiple simulation methods, integrating structural mechanics, fluid dynamics control, thermodynamics, or acoustic analyses.

Using the SimScale simulation platform, designers could validate experimental results, running parametric studies and mixing different simulations methods. Valve design optimization could be used to reduce pressure drops, homogenize flow, or to improve laminar and turbulent mixing. SimScale platform offer a rich set of simulation functionalities for various valves such as gate, butterfly, ball, globe, and control valve.

Very recently announced, the SimScale Public Projects started with 200 projects ready to be used for free as templates for any community member, including several valve analyses.

One of projects simulates the “water flow through a globe valve”. [3]

CAD model of a globe valve on SimScale

• The project is based on a CAD model provided by Krzysztof Buczak.
• In the first simulation step the inner fluid flow volume of the valve is extracted with SpaceClaim functionality
• SimScale Hex-dominant mesh operation is used for the inner volume meshing
• Higher gradients from central region are solved with a volume refinement method.
• A refined viscous boundary layer is additionally added to the mesh.
• Meshing is carried out on two cores and the resulting mesh consists of 460,000 cells – figure 1.
• The mesh is used to set up a turbulent, steady-state, incompressible fluid flow analysis.
• The k-epsilon model is chosen to account for the turbulence effects.
• The simulation is set up as a steady-state simulation, however there might be several transient turbulent effects that will not be captured with this simulation setup.Valve simulation with SimScaleIt is therefore rather a rough first analysis of the flow. In order to capture more details of the flow, a finer mesh could easily be set up and a transient analysis type used.
• Actual simulation was — then carried out on four cores which took around 50 minutes.
• The residual plots can be watched live during the simulation in order to track the progress of the simulation.
• As soon as the simulation is finished, the results can be analysed and visualized in the integrated post-processing environment (image above).

 

All the projects presented in this article can be imported into your own workspace and used as templates. Feel free to browse the SimScale Public Projects for other interesting simulations.

If you would like to learn more about how the SimScale simulation platform can help you test and optimize your valve design, you can find more information here.


References:

[1] “Industrial Valves Market by Type, by Application, and by Region”– Global Trends & Forecasts to 2019, Research and Markets, May 2015

[2] “Process Design of Valves” – KLM Technology Group Project Engineering Standard, April 2011

[3] “Water flow through globe valve simulation analyse” – David Heiny, SimScale Public Projects, 2015

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