Cavitation evolution and damage by liquid nitrogen in a globe valve
Xia Zhou, Xiaoqin Zhi, Xu Gao, Hong Chen, Shaolong Zhu, Kai Wang, Limin Qiu, Xiaobin Zhang
Abstract
Valves are key components of the safety of fluid transportation systems because of induced disturbance and cavitation damage in them. In this study, a 2D model of a cryogenic globe valve with liquid nitrogen (LN2) as working fluid was established by Fluent, and thermal effects were specially considered in the simulation. The validity of the LN2 cavitation model was verified by the experimental data of hydrofoil LN2 cavitation from earlier studies by NASA. Cavitation characteristics of LN2 in the cryogenic globe valve under three typical working conditions were investigated. The average pressure and pressure pulse at different positions of the wall were further studied to reveal cavitation risks from fatigue and vibration. Results show that with similar valve structure and openings, the pressure pulsation frequencies of LN2 are lower than those of water, and the shape and location of the cavitation clouds also show significant differences. For LN2 cavitation, an extended period of valve opening at 66% should be avoided since its pressure pulse peak is the largest compared to openings of 33% and 100%, and reaches 5×107 Pa. The opening of 33% should also be monitored because of the large torque caused by the pressure difference between the two sides of the valve baffles. To prevent resonance, a critical state for the valve opening and the connecting pipe length is proposed. These predictions of cryogenic cavitation in the globe valve are helpful for the safe and reliable operation of cryogenic fluid transport systems.