INDUCER CAVITATION INSTABILITIES AND SUPPRESSION ON WIDE OPERATING RANGE

Turbopump is the heart of liquid rocket engine, cavitation instabilities may occur under certain working conditions inside the pump, then the vibration magnitude of turbopump magnifies remarkably, impairing working reliability of the liquid rocket engine. This paper takes the inducer which determines the turbopump cavitation resistance ability as the research object, investigates the cavitating flow characteristics inside an inducer under wide range flow working conditions through visualization experimental techniques and numerical simulation, obtains the whole cavitation performance curves at 60% ~ 120% designed flow rate. A rotating cavitation suppression method based on casing modification has been proposed, and its working mechanism is clarified. It is found that the cavitation resistance ability of the investigated inducer is enhanced with the flow rate decreasing. Cavitation occurs inside the leakage vortex firstly, then the leakage vortex cavitation develops downstream along the suction surface as cavitation number decreases, influencing the angle of attack of the adjacent blade. Remarkable super synchronous rotating cavitation is induced under small flow rate range. The head breakdown occurs until cavitation extends to the outlet of impeller passage. When a step is set on the housing near blade tip leading edge, the stable cavitation performance is not influenced. However, the leakage vortex cavitation development tendency is changed, it swings toward upstream. Then the influence to the angle of the adjacent also weakens, the rotating cavitation under whole flow rate working condition is suppressed effectively. The investigation shows definite guiding significance on reducing the turbopump vibration magnitude, then developing the working reliability of liquid rocket engine.