During the development stage of the liquid hydrogen turbopump for the main engine LE-7A of the H-IIA rocket, a new type of cavitation instability was observed. This instability occurs at lower cavitation numbers where the head of the inducer starts to decrease due to choke. The disturbance rotates around the rotor at about 50% of the inducer rotational speed. So, it is called "rotating choke." In order to predict the instability, a cavity model with a cavity wake is developed. The region of instability and the frequency predicted by the model are in agreement with experiment. Discussions are made as to the relationship between rotating choke and rotating cavitation.
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