Design optimisation of a safety relief valve to meet ASME BPVC section I performance requirements

The understanding of fluid flow behaviour within safety relief valves invariably requires knowledge of strong pressure and velocity gradients with significant levels of turbulence in three-dimensional flow environments. In the case of gas service valves - the focus of this thesis - these flows will be super-sonic with multidimensional shock formations resulting in challenging design conditions. This thesis takes advantage of the development and validation of computational fluid dynamic (CFD) techniques in recent years to reliably predict such flows and investigate how the techniques can be used to produce better performing safety valves. Historically OEMs will have relied on an experimental based design approach using feedback from test data to guide the evolution of a valve design. Unfortunately, due to the complexity of these devices this method could require much iteration. However, it is now possible to combine CFD techniques and optimisation algorithms to search for improved designs with reduced development times. To date these techniques have had limited exposure within valve design studies. This thesis investigates the development of a numerical based design procedure by combining validated CFD models optimisation techniques to seek valve trim geometries that improve opening and closing behaviour. The approach is applied to an ASME Section VIII certified valve and seeks to modify the internal trim to satisfy the improved performance requirements stipulated in Section I of the ASME Boiler and Pressure Vessel Code.The understanding of fluid flow behaviour within safety relief valves invariably requires knowledge of strong pressure and velocity gradients with significant levels of turbulence in three-dimensional flow environments. In the case of gas service valves - the focus of this thesis - these flows will be super-sonic with multidimensional shock formations resulting in challenging design conditions. This thesis takes advantage of the development and validation of computational fluid dynamic (CFD) techniques in recent years to reliably predict such flows and investigate how the techniques can be used to produce better performing safety valves. Historically OEMs will have relied on an experimental based design approach using feedback from test data to guide the evolution of a valve design. Unfortunately, due to the complexity of these devices this method could require much iteration. However, it is now possible to combine CFD techniques and optimisation algorithms to search for improved designs with reduced development times. To date these techniques have had limited exposure within valve design studies. This thesis investigates the development of a numerical based design procedure by combining validated CFD models optimisation techniques to seek valve trim geometries that improve opening and closing behaviour. The approach is applied to an ASME Section VIII certified valve and seeks to modify the internal trim to satisfy the improved performance requirements stipulated in Section I of the ASME Boiler and Pressure Vessel Code