CFD assessment of shock flow evolution during oxygen pressure surge test

The objective of this study is to perform detailed CFD assessment of the flow phenomena during the oxygen pressure surge test (OPST) at 30 MPa based on the ISO 10297 standard. Transient CFD simulations with high temporal resolution of two geometries have been carried out using the OpenFOAM software: (i) a 1000 mm long, 5 mm diameter pipe and (ii) a 750 mm long, 14 mm diameter pipe. A highlight of this study is the implementation of the opening behavior of the quick opening valve from test data as an input in the CFD simulation. This is a novel approach which results in a very realistic simulation behavior of the oxygen flow from the high-pressure driver section into the low-pressure driven section. Real gas properties, high-resolution meshing, and shear stress transport turbulence modeling are used to obtain a realistic prediction of the entire flow-field and the associated flow phenomena (e.g. supersonic shock flow, rapid compression at the end-wall, shock wave reflection etc.) during the OPST. It is observed that pressure and temperature surge near the end-wall is more pronounced in the 1000 mm length pipe implying that pipe geometry is an important factor influencing shock strength. This study thus aims to bridge the existing lack of knowledge about the flow phenomena during OPST using CFD oriented approach to aid engineers in designing oxygen products with a high degree of safety.