Numerical Investigation and Temperature Field Analysis during Liquid Hydrogen Bubble Collapse in Confined Micro-Clearance
摘要
In the micro-clearance of the valves and sealing structures of liquid hydrogen (LH2) storage tanks, bubbles occur due to heat leakage. The sudden rising of pressure causes bubbles to collapse, resulting in pressure and temperature fluctuations that impact the sealing surface and the valve. In this paper, the cryogen cavitation model is modified by considering the thermal effect, surface tension, and viscosity. The bubble collapse inside micro-clearance is investigated by the modified cavitation model and volume of fluid (VOF) method. Transient pressure and temperature at the bubble center during collapse are recorded and evaluated. The effects of micro-clearance height, dimensionless bubble diameter, and bubble vertical position on bubble collapse and bubble morphology are investigated. To reduce the cavitation erosion on the walls, the frequency and time-frequency characteristics of the pressure oscillations induced by bubble collapse are analyzed by Fast Fourier Transform (FFT) and Wavelet Transform (WT). Furthermore, the temperature and pressure field variation and oscillation mechanisms are analyzed by Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD). The analytical results reveal the LH2 bubbles collapse mechanism within the micro-clearance. The results provide a certain extent of reference for optimizing the structure of micro-clearance.