Coupled periodic pressure pulsation characteristics and influencing factors of aircraft piston pumps under different pump source systems

Existing research on pressure pulsation in piston pumps primarily focuses on pump-internal mechanisms and parameter sensitivity, while the dynamic role of the discharge line and its bidirectional coupling with the pump outlet is often underrepresented. Consequently, the coupled periodic pulsation observed in aircraft Pressure-Compensated Piston Pumps (PCPPs) and the fact that identical pump models can exhibit markedly different outlet pulsation behaviors in different hydraulic systems cannot be satisfactorily explained by pump-only models. To address this gap, this paper proposes a forward, fully coupled prediction framework that integrates (i) a lumped-parameter dynamic model of the PCPP (including compensator-driven variable-displacement dynamics) and (ii) a one-dimensional transient discharge-line model solved by the Method of Characteristics (MOC). The pump outlet flow is imposed as the upstream boundary excitation of the line, and the resulting pump-side line pressure is fed back to the pump outlet chamber and control dynamics in a time-marching closed loop. Experimental measurements under constant-pressure variable-displacement operating conditions are used to validate the proposed model at multiple operating points. The results demonstrate that discharge-line parameters and operating conditions reshape the harmonic energy distribution and can selectively amplify specific harmonic components, thereby producing the observed coupled periodic pulsation. The proposed framework provides practical guidance for pulsation mitigation and discharge-line design, and also supports condition monitoring and fault diagnosis based on pulsation features.