The effects of cavitation on the control performance of a cryogenic valve

Abstract

Cryogenic valves have been widely used in the transmission systems of cryogenic fluid mediums such as LNG, LN₂, LO₂ and other liquefied gas, which plays important roles in the stability and reliability of the system operation. Cavitation makes serious erosion and damage on the valve core and pipeline surface, which leads to the leakage and noise problems in cryogenic valves. Cryogenic cavitation phenomenon usually produces vibration and noise hazards, which significantly affect the stable operation of the system. In this study, Based on the original ZGB cavitation model, combined with the thermodynamic effect of cryogenic fluid, the cavitation model is modified, and a cavitation model suitable for cryogenic fluid is obtained. The accuracy and applicability of the modified cavitation model are verified by the combination of experiment and numerical simulation. Taking different openings as the research variables, the cryogenic cavitation under different openings was obtained, and the influence of cavitation on the control performance of the cryogenic ball valve was analyzed. The results show that when the spool is in a large opening, cavitation has a great influence on the control performance of the ball valve. The volume and flow instability of the cavity change with the opening. And the spatial and temporal distribution of the vortex structure in the cavitation flow field is highly consistent with the evolution of the cavitation. The energy loss in the cavitation flow field is quantified by the entropy characterization method, and the evolution process of cavitation is characterized by different types of entropy production distribution. The results show that the outlet of the spool is the concentrated area of entropy production distribution, and in the cavitation flow field, the entropy production caused by direct dissipation (EPDD) and the entropy production caused by turbulent dissipation (EPTD) account for the main part of the total entropy production in the cavitation flow field.