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.
The Impedance Characteristics of Fluid Power Components: Relief Valves and Accumulators
This paper describes an experimental and theoretical investigation of the impedance characteristics of various relief valves and an accumulator. The test programme involved the measurement of pressure ripples at three locations in a specially designed test circuit. From these measurements, the impedance of a component was evaluated as a function of frequency. The experimental results are compared with mathematical models. For a single-stage relief valve, a simple orifice model has been found to be adequate. For two-stage valves, a much more complex model was considered. This was found to predict the basic trends but was not accurate. Tests on an accumulator yielded results which correlated well with a relatively simple mathematical model. However, it is difficult to quantify the model parameters. It is concluded that for the more complex components used in hydraulic systems it is necessary to measure the impedance characteristics rather than predict them. There is a need to adopt a standard test procedure for this purpose.
Hydrodynamic noise in water-supply systems for nuclear power plants
The results of vibro-acoustic investigation of laboratory model of the fourth circuit of nuclear power plant are presented. It is shown that the spectrogram of hydrodynamic noises is the solid spectrum, on the background of which there are the pronounced discrete components. The centrifugal pump and the throttling orifice are the main reasons of vibrations and noise. The recommendations of how to minimize the hydrodynamic noise in such systems are given. The results of investigation can be used for stationary and floating nuclear power plants and also for other types of power plants.