Abstract
This paper presents characteristics of discharge pulsating pressure generated by an external gear pump. Based on the theoretical and experimental examinations, it is pointed out first that the former mathematical model for flow ripple is insufficient in the case of high working pressure or low pump speed. It is found experimentally that a large amount of leakage through relief grooves takes place intermittently in the vicinity of the central position of trapping. This leakage affects dominantly the fluctuation of a discharge flow (flow ripple), especially its higher harmonic components. The calculated values of discharge pressure pulsations based on the presentmathematical model for flow ripple taking the leakage mentioned above into consideration agree well up to about tenth harmonic with the experimental values.
