Analysis of Complex flows in Safety Valves using CFD modelling techniques.
Lead Research Organisation:
University of Strathclyde
Department Name: Mechanical and Aerospace Engineering
Abstract
Safety valves are an important element of pressurised plant safety and have well established empirical based design and testing methods. However, these methods are usually supplemented by testing which is often limited due to the availability and expense of facilities: testing is usually restricted to air, relatively low pressure and low mass flowrates and rarely cover the full range of a designed valve. Furthermore, a general lack of design knowledge exists for complex flows involving multiphase, flows with phase change and complex fluid mixtures. To overcome these issues computational modelling can offer reduced testing time and better insight into valve design and operation and it is in this context that this project is proposed. The project will build upon previous modelling and testing work carried out at Strathclyde University and consist initially of two main elements (i) use of CFD to model transient processes in safety valves and (ii) improvements in flow physics to better predict valve flow conditions under phase change processes.
The study will be use the commercial CFD code FLUENT as a basis of study and for objective (ii) as platform for the development of new models. The model results will be compared with inhouse experiments in the case of (i) and external experiments in the case of (ii). If time permits then transient two phase tests will be conducted and compared to model results.
The study will be use the commercial CFD code FLUENT as a basis of study and for objective (ii) as platform for the development of new models. The model results will be compared with inhouse experiments in the case of (i) and external experiments in the case of (ii). If time permits then transient two phase tests will be conducted and compared to model results.
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509760/1 | 01/10/2016 | 30/09/2021 | |||
| 1811628 | Studentship | EP/N509760/1 | 01/10/2016 | 30/09/2020 | Christopher Doyle |
| Description | Pressure relief valves (PRV's) and their reliable performance is crucial for the safety of pressurised components across a variety of engineering industries. In this research so far, two different types of PRV's conforming to ASME 8 standards has been modelled using computational fluid dynamics (CFD) to account for the transient fluid-structure interaction processes. The main objective is to assess its accuracy against experimental measurements and assess the validity of commonly used quasi-steady analysis approaches. The commercial CFD code FLUENT was used to investigate the flow behaviour for air at various pressures by measuring the flow rate and aerodynamic forces acting on the valve disc for both steady state and transient conditions. To capture the dynamic behaviour of the PRV during transient simulation, a hybrid dynamic mesh methodology was developed alongside a user defined function (UDF) to provide a robust solution to modelling PRV dynamics using CFD. Once modelled, the transient dynamic mesh simulation would be able to provide a history of piston movement with time to highlight overpressure and blowdown characteristics. Experimental testing was performed within the pressure testing facility at the University of Strathclyde and Broady Flow Control Ltd. This testing program combined both steady state and transient measuring techniques to enable validation of the computational model for both conditions. An opportunity was also available in this study to compare the accuracy of steady state CFD simulation and the assumption of quasi steady conditions to direct transient simulation on capturing the dynamics of the PRV. Such a study has not yet been performed within available literature therefore it seemed essential to build upon previous validation work using steady state approaches. It was found that steady state simulation using a modified Langtry and Menter Transition SST turbulence model was capable of predicting steady state aerodynamic forces to within 1% average accuracy and flow rate to within 2% average accuracy of experimentally measured values across the full lift range. The transient simulation was capable of predicting overpressure to within 1.5% and blowdown to 0.3% as well as accurately modelling the dynamic motion of the PRV. Significant differences in flow structure between transient dynamic mesh and steady state approaches were also observed, questioning the validity of quasi-steady analysis approaches. It is therefore recommended to accurately capture the dynamics of PRV motion using CFD; a transient dynamic mesh approach should be adopted, if feasible, at the cost of increased computation compared to steady state modelling methods. Work is still ongoing for the Henry Technologies PRV with research to be published within the next few months and work will be performed to test the viability of utilising multiphase physics within transient models with experimental validation. |
| Exploitation Route | If a valve manufacturer was to adopt the technology and processes used within the work performed within this PhD the key benefits would be; Improved simulation techniques offer shorter development times, enhanced product performance through virtual design, enriched marketing literature indicating a technical advanced company and most of all to be able to determine valve performance for conditions that are outwith the capability of in-house test facilities, thus reducing risk and increasing reliability. The basis of the PhD studies and the extension into the work placement is established on the evolvement of simulation models into the 'digital twin' concept of total virtual design, manufacturing and operation and sits within the Manufacturing the Future theme of the UK industrial strategy and specifically the Information and communications (ICT) category of the strategy. The development of 'virtual twins' rely on the creation of dynamic models to simulate correct component functionality and its relationship with other components when built into engineering systems. This is conceived to be the future of engineering manufacturing and at its foundation are reliable simulation models. When considering valve operation, due to the inability to test for all operational conditions (fluids, pressures temperatures) pushes engineers into a reliance on simulation models. Developed and validated high fidelity models of safety valves are only beginning to appear in the academic community. How these models can be realised within a manufacturing environment will be investigated through industrial involvement. |
| Sectors | Aerospace, Defence and Marine,Agriculture, Food and Drink,Chemicals,Construction,Digital/Communication/Information Technologies (including Software),Energy,Environment,Manufacturing, including Industrial Biotechology,Transport |
| Description | The commercial CFD code FLUENT was used to investigate the flow behaviour for air at pressures of up to 100 bar by measuring the flow rate and aerodynamic forces acting on the valve disc for both steady state and transient conditions. To capture the dynamic behaviour of the Pressure Relief Valve (PRV) during transient simulation, a hybrid dynamic mesh methodology was developed alongside a user defined function (UDF) to provide a robust solution to modelling PRV dynamics using CFD. Once modelled, the transient dynamic mesh simulation would be able to provide a history of piston movement with time to highlight overpressure and blowdown characteristics. This has allowed valve manufacturers to use generated data to gain a better understanding of the performance of their valves through enhanced visualisation and crucial data output. As a result, the modelling techniques developed can be used by manufacturers and researchers in the future to further improve/optimise performance of valves and gain a better understanding of the fluid structures and working principles of PRV design. This was also allow manufacturers to reduce prototyping and testing costs during the early design phase of valve development. |
| First Year Of Impact | 2018 |
| Sector | Aerospace, Defence and Marine,Energy,Environment,Manufacturing, including Industrial Biotechology |
| Impact Types | Economic,Policy & public services |
| Description | EPSRC National Productivity Investment Fund (NPIF) Innovation Placements |
| Amount | £3,695 (GBP) |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 01/2019 |
| End | 04/2019 |
| Title | Transient Analysis of Pressure Relief Valves using Dynamic Mesh methods |
| Description | To capture the dynamic behaviour of the Pressure Relief Valve during transient simulation, a hybrid dynamic mesh methodology using dynamic layering and remeshing was developed alongside a user defined function (UDF) to provide a robust solution to modelling PRV dynamics using CFD. Once modelled, the transient dynamic mesh simulation would be able to provide a history of piston movement with time to highlight overpressure and blowdown characteristics |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2019 |
| Provided To Others? | No |
| Impact | The ability for valve manufacturers/designers/researchers to use the created design tool during the early design phase to gain an understanding of valves performance. This will reduce costs for prototyping and testing as well as provide a tool for optimisation to achieve the desired performance. In addition, further funding is likely from Weir Advanced Research Centre to continue work on the developed model to provide design optimisation tool. |
| Description | Collaborations with UK Pressure Relief Valve Manufacturers |
| Organisation | Henry Group |
| Country | Hong Kong |
| Sector | Private |
| PI Contribution | To provide both a steady state and transient dynamic mesh model to both manufacturers capable of within acceptable accuracy to replicate actual valve performance measured experimentally for single phase flow. Option to provide model capable of capturing multi phase physics. Sponsored industrial placement from EPSRC NPIF funding took place at Henry technologies for 3 months. |
| Collaborator Contribution | Broady provide pressure relief valves for experimental validation/evaluation costing approximately (£500-£1000), access to test data, solidworks models, expertise and test facilities. Values of the facility in order of £100k-£200k. Henry provide access to high pressure test facilities and PRV's. The valves are in £100-500 range. The facility is likely in the £50k -100k region |
| Impact | Both a steady state and transient dynamic mesh model to both manufacturers capable of within acceptable accuracy to replicate actual valve performance measured experimentally for single phase flow. This could help designers to optimise designs, gain a greater understanding of valve performance earlier in the design process and reduce costs in terms of prototyping and testing. Collaboration is both experimental and mathematical (Computational Fluid Dynamics) based. |
| Start Year | 2016 |
| Description | Collaborations with UK Pressure Relief Valve Manufacturers |
| Organisation | VALVITALIA |
| Department | BROADY FLOW CONTROL |
| Country | Italy |
| Sector | Private |
| PI Contribution | To provide both a steady state and transient dynamic mesh model to both manufacturers capable of within acceptable accuracy to replicate actual valve performance measured experimentally for single phase flow. Option to provide model capable of capturing multi phase physics. Sponsored industrial placement from EPSRC NPIF funding took place at Henry technologies for 3 months. |
| Collaborator Contribution | Broady provide pressure relief valves for experimental validation/evaluation costing approximately (£500-£1000), access to test data, solidworks models, expertise and test facilities. Values of the facility in order of £100k-£200k. Henry provide access to high pressure test facilities and PRV's. The valves are in £100-500 range. The facility is likely in the £50k -100k region |
| Impact | Both a steady state and transient dynamic mesh model to both manufacturers capable of within acceptable accuracy to replicate actual valve performance measured experimentally for single phase flow. This could help designers to optimise designs, gain a greater understanding of valve performance earlier in the design process and reduce costs in terms of prototyping and testing. Collaboration is both experimental and mathematical (Computational Fluid Dynamics) based. |
| Start Year | 2016 |
| Title | Ansys Fluent and Ansys Workbench |
| Description | Computational Fluid Dynamics (CFD) solver and meshing product. |
| Type Of Technology | Software |
| Year Produced | 2019 |
| Impact | Development of CFD models capable of accurately modelling pressure relief valves. |
| URL | https://www.ansys.com/en-gb/products/fluids/ansys-fluent |