Comparative analysis of flow field characteristics and cavitation mechanisms in liquefied natural gas ball valves with two different valve core structures

Abstract

Cryogenic ball valves are widely used in transportation systems involving liquefied natural gas (LNG), liquid nitrogen, and other low-temperature media, where cavitation may occur during operation and significantly affects the flow structure, energy transfer, and valve performance. In this study, three-dimensional numerical simulations of O-type and V-type LNG ball valves are conducted based on the Schnerr–Sauer cavitation model to systematically investigate the flow resistance characteristics, cryogenic cavitation evolution, vortex structures, and entropy production at different valve openings. Within the valve opening range of 30%–90%, the flow coefficient (Kv) increases from 0.11 to 0.85 for the O-type valve and from 0.015 to 0.20 for the V-type valve. Cavitation reaches its maximum intensity at 70% valve opening for both valve configurations, with the V-type valve exhibiting more severe cavitation. Vortex analysis based on the Q-criterion reveals a strong coupling between cavitation regions and high-intensity vortex structures, where vortex entrainment accelerates bubble generation and transport. Entropy production analysis further demonstrates that the O-type ball valve exhibits a larger total entropy production area and a higher peak of direct dissipation, while the entropy generation of both valves is primarily concentrated near the valve core outlet. These results clarify the effects of valve core geometry on cryogenic cavitation dynamics, flow evolution, and irreversible energy loss, providing theoretical guidance for structural optimization, cavitation suppression, and reliable operation of cryogenic ball valves.