|关键词: 空化模型 Omega涡识别 相变系数 附着空化 叶顶间隙泄漏涡空化
|A self-adaptive cavitation model based on Omega vortex identification theory
QU Nianchong1, XU Kaifu1, XIANG Le1, LIN Ronghao2, DANG Xiaorui1
1.Xi’an Aerospace Propulsion Institute，Xi’an 710100，China;2.Science and Technology on Liquid Rocket Engine Laboratory，Xi’an Aerospace Propulsion Institute， Xi’an 710100，China
|There are many complex types of cavitation in the turbopump of liquid rocket engine， and the occurrence mechanism is different. The existing cavitation numerical calculation methods usually use a set of models to predict all types of cavitation， which has certain deficiencies in the prediction accuracy of cavitation. To improve the calculation accuracy of complex cavitation flow， a self-adaptive cavitation model was proposed. Based on the advanced Omega vortex identification theory and ZGB cavitation model， a self-adaptive adjustment method for phase-transition coefficient was established. Two types of typical cavitation （attached cavitation and leakage vortex cavitation） in turbopumps were taken as the research objects， and the simulation method was verified by hydrofoil experiment data. Firstly， the differences of several vortex identification methods were compared. The result suggests Omega method is not sensitive to threshold and has clear physical meaning， which can be used as the value basis of the phase-transition coefficient. The effect of phase transition coefficient on attached cavitation and leakage vortex cavitation and mechanism of these two cavitations were analysed. The results show that compared with the ZGB model， the prediction accuracy of the self-adaptive model for leakage vortex cavitation is improved by 181% in the case of large clearance and 27% in the case of small clearance. The prediction of attached cavitation is closer to the experimental results. Attached cavitation is the reason of vortex shedding on suction surface. The vortex band and the shear layer cavitation of tip leakage flowfield are formed by the interaction of tip leakage vortex and separation vortex.
|Key words: Cavitation model Omega vortex identification Phase-transition coefficient Attached cavitation Tip leakage vortex cavitation