Relationship between the Complex Parameters of Normalized Termination Impedance and the Standing Waves of Pressure Pulsation in a Hydraulic Pipe Line: (Analysis of the Transition of Resonant Mode by Numerical Calculation)@@@(数値計算による共振モードの遷移の解析)

Abstract

It is well known that the amplitude of pressure pulsation becomes extremely high when the frequency of the pump rotational speed coincides with the resonant frequency of the pressure pulsation standing waves. In the previous report, the authors investigated the relationship between the resonant modes of the standing wave arising in the connecting pipe and the termination characteristics of the hydraulic circuit. Although the influence of the two terminations, a restrictor and volume, on the resonant modes was clarified, the termination impedance contains only a real number or a purely imaginary number in terms of the complex characteristic. In this report, a further investigation of the influence of the complex parameters of termination impedance characteristics is undertaken. In particular, the non-dimensional pressure pulsation in the connecting pipe is examined by the numerical calculation to understand the resonant phenomena of a standing wave for the complex parameters of termination impedance. Consequently, the transition of the resonant mode between the “both ends closed” mode and the “pump end closed and termination end opened” mode is confirmed. The characteristics of the transition resonant mode are clarified, and it is found that pressure pulsation also becomes extremely high under the transition resonant mode conditions.