Impact of Flow Rate on Turbopump Inducer Blade-to-Blade Interaction During Local Cavitation Instability

Abstract

In turbopump inducers, cavitation on one blade can change incidence on the following blade, and this “blade-to-blade interaction” can lead to local cavitation instabilities such as alternate blade cavitation (ABC) and supersynchronous rotating cavitation. However, how the inducer operating condition (e.g., flow rate) affects the blade-to-blade interaction is still unknown. Therefore, for the first time, the dependence of blade-to-blade interaction on the inducer flow rate has been measured via fluorescent particle image velocimetry (fPIV) and high-speed visualization. The blade-to-blade interaction depends nonlinearly on the flow rate and is maximized at a certain flow rate, or certain incidence (αmax). At the flow rate corresponding to αmax, the cavity trailing edge on the leading blade is located near the inducer throat, and a sink-like flow is generated closest to the following blade’s leading edge, maximizing the blade-to-blade interaction. As the flow rate either increases or decreases from the flow rate corresponding to αmax, the trailing edge of the leading blade cavity moves farther away (upstream and downstream) from the inducer throat, weakening the blade-to-blade interaction.