Establishment of Prediction Model for Cavitation Surge Frequency and Onset in an Inducer Considering Dynamic Characteristics of Cavitation Compliance and Mass Flow Gain Factor

An accurate prediction method of cavitation surge is desired to design a reliable turbopump for rocket engines that allow complex operational sequences such as controlled reentry and landing. Therefore, the paper aims to develop a novel model that enables accurate predictions of both frequency and onset of cavitation surge by considering dynamic characteristics of cavitation compliance K and mass flow gain factor M. The paper conducts both experimental and numerical studies in an inducer known to cause cavitation surge. First, characteristics of cavitation surge including frequency and occurrence conditions are experimentally surveyed. Secondary, K and M for the studied inducer are numerically obtained by steady RANS simulations. Then, the one-dimensional model is initially established based on the premises acquired by performed experiments and applied to cavitation surge predictions using quasi-statically evaluated K and M. As a result of comparisons with experiments, the cavitation surge frequency is adequately evaluated by the established model, whereas the cavitation surge onset fails to be estimated only using quasi-static parameters. The new model is thus proposed by including dynamic characteristics of K and M, and it is mathematically clarified that phase properties of K and M may play a key role to trigger cavitation surge. By presuming adequate values of dynamic characteristics based on past literatures, consequently, the developed model succeeds in accurate predictions of the cavitation surge onset in the experiment. This evidences that dynamic characteristics of K and M are essential to predict cavitation surge quantitatively.