Effect of the Opening Degree on Evolution of Cryogenic Cavitation Through a Butterfly Valve

Butterfly valve is widely used to transport cryogenic medium such as liquid natural gas (LNG), liquid nitrogen and so on. When the pressure of cryogenic fluid is lower than the saturated vapor pressure corresponding to the local temperature, the cryogenic fluid will produce the phase transformation from liquid to gas, which is called as cryogenic cavitation. Cavitation phenomenon is the main cause of cavitation erosion, vibration and noise, which seriously affects the stable operation of the system and the lifetime of the valves. Cryogenic medium is more easily cavitated in the process of transportation and regulation due to its unique thermal sensitivity. In order to explore the evolution mechanism of cryogenic cavitation through butterfly valves, numerical simulations were carried out to study the dynamic evolution of cryogenic cavitation through a butterfly valve model at different valve opening degrees. By considering the thermal effect of cryogenic medium, the traditional cavitation model is modified and verified by experimental results. The evolution including generation, development and collapse of cryogenic cavitation is observed and discussed in details at each valve opening degree. The relationship of cryogenic cavitation and vortex structure is revealed and entropy production is obtained to indicate the intensity of dynamic evolution of cryogenic cavitation through butterfly valve.