Development research of reflection-absorption compound type fluid pulsation attenuator
Based on the disadvantages analysis of the existing fluid pulsation attenuator, two reflection-absorption compound type of fluid pulsation attenuators which are both composed of a chamber and a mass-spring-damping system are developed: in-line reflection-absorption compound type of fluid pulsation attenuators (in-line RAFPA) and side-branch reflection-absorption compound type of fluid pulsation attenuators (side-branch RAFPA). The transfer matrix models of the two attenuators are established as well as expansion chamber attenuator and Helmholtz resonator. Based on the transfer matrix model, the transmission loss of the four attenuators is given out to evaluate their attenuation characteristic. The attenuation characteristic comparisons of in-line RAFPA with expansion chamber attenuator and side-branch RAFPA with Helmholtz resonator are carried out respectively. And the effect of the mass-spring-damping system to in-line RAFPA and side-branch RAFPA is investigated. The simulation reveals the two reflection-absorption compound type of fluid pulsation attenuators have better attenuation characteristic and are more compact than expansion chamber attenuator and Helmholtz resonator.
Reducing low-frequency vibration in hydraulic systems by means of Helmholtz resonators
Low-frequency damping systems for the pressure pulsations in a pipeline system are investigated in a mockup of the fourth loop of a nuclear power plant. The acoustic characteristics of Helmholtz resonators are calculated. Acoustic tests are conducted to reduce the vibration at the blade frequencies of the circulation pump. It is shown that the efficiency of such structures depends both on the accuracy with which the resonator eigenfrequencies are matched to the blade frequency of the vibration source and on the resonator location within the pipeline system.
Research on Pulsation Attenuation Characteristics of Silencers in Practical Fluid Power Systems
Abstract The pulsation attenuation characteristics of silencers in practical fluid power systems are investigated theoretically and experimentally in terms of the insertion loss characteristics, taking the every key circuit-design factors including the pump and the load into consideration, so as to develop an useful CAE design tool for reducing the system audible noise level through the use of a fluid-borne vibration control technique. A new expression for the insertion loss characteristics is also proposed which makes the physical elucidation of its complex characteristics easy and helps to search for the optimum insertion location efficiently. Particular attention has been paid to both the theoretical determination of the optimum insertion location and the optimum design of silencer for the specified hydraulic circuit. The simulated results of the insertion loss characteristics agree with the experimental results with sufficient accuracy for practical use up to around 5th harmonic of the pump-induced harmonic pressure pulsation. Further, it is shown that our developed new silencer called a “variable-resonance mode type side-branch resonator” has proven to be very successful for reduction of audible noise also in application to a real hydraulic excavator.