Cavitation flow characteristics and optimization of high-pressure pumps in hydraulic system of aircraft control surfaces

To break the monopoly of key technologies for high-pressure piston pumps in the list of the United States，and aiming to satisfy the requirement for precise rudder control of large civil aircraft during navigation，this study conducts numerical simulations and optimization of internal flow characteristics in the pumps based on full cavitation models and compressible models. The numerical simulations are validated by a series of experiments. The causes of the formation of flow valleys and peaks are revealed by analyzing the flow characteristics，the way cavitation impacts flow pulsation is discovered，and a method to suppress cavitation in the piston chamber is proposed. Conclusions：Backflow is the main cause of the drainage flow valley. The drainage flow peak（i. e. ，pressure overshoot）is caused by two factors. First，the inertial impact of backflow hydraulic oil causes a sudden increase in cavity pressure. Second，hold pressure due to untimely and incomplete overflow after the end of the backflow induces the pressure overshoot. Gas bubbles in the piston chamber absorb the“intended boost”and prolong the back-up time，thus reducing the flow valley. A mathematical model for suppressing the cavitation of the piston chamber at the invariable theoretical flow rate is established by innovatively coupling the piston chamber flow rate equation and the pressure drop equation from the perspective of pressure drop to solve the problem of theoretical flow rate reduction resulted from suppressing the piston chamber cavitation. Based on the model，two methods are proposed to suppress the cavitation of the piston chamber without changing the theoretical flow rate，providing theoretical solutions for the development of military axial piston pumps. © 2023 AAAS Press of Chinese Society of Aeronautics and Astronautics. All rights reserved.