An experimentally validated multifidelity hybrid model for analyzing the pressure variation of a relief system

Abstract

In a relief system, the pressure variation in the system is often caused by the operations of the pressure control elements such as the pressure relief valve and ball valve, in addition to the pressure fluctuations in the pressure resources. This pressure variation couples with the acoustics or the motion of passive pressure control elements, which may result in system malfunction. To investigate the principles of the pressure variation in a relief system including a reservoir, a pipeline and a spring-loaded pressure relief valve, a multifidelity hybrid model combining the method of characteristics (MOC) and computational fluid dynamics (CFD) method is proposed. In the multifidelity hybrid model, the characteristics of the pressure resources are modeled using their performance curves, the compressible gas transmitted in the pipe is calculated by one-dimensional MOC, and the air flow in the valve as well as the valve motion is simulated by a two-dimensional CFD model. To validate the model, analyses are conducted with a 1:1 scale test rig and a full CFD model. The comparison of the results shows that both the multifidelity hybrid model and the full CFD model can accurately capture the pressure fluctuations in straight pipelines induced by valve closure and predict the forms of valve motion, but the calculation speed of the multifidelity hybrid model is four times faster than that of the full CFD model.