Analysis of fluid vibration transfer path and parameter sensitivity of swash plate axial piston pump

Taking swash plate axial piston pump as the research object,the mechanism of fluid vibration and transfer rule are analyzed.The pump shell can be assumed as the ultimate recipient of vibration transmission,the path model and differential equations from the fluid to the shell are established.The parameters of the path model are determined by the simulation software,and the mathematical model is solved by the simulation software.And time/frequency domain analysis of vibration acceleration of shell is presented.Based on the different influence of various parameters in the transfer path model on transfer characteristics and vibrational recipients,the time-varying parameters are studied by using sensitivity analysis theory,and the influence of the structural parameters on the vibration characteristics of vibration subject is quantitatively analyzed.The research in the paper provides theoretical basis for vibration analysis and structure parameter optimization of axial piston pump.

Fluid Vibration Induced in T-Junction with Double Side Branches

A T-junction is a fundamental fluid element prevalent in pipe networks of water supplies and power plants. In the present study, a double T-junction was investigated for flow instability and fluid vibration. Both axi-aligned and skewed double T-junctions are examined from viewpoint of flow instability. With single-phase flow in an open-ended double T-junction, fluid vibration is induced in both side branches because of a high shear rate with a point of inflection. The frequency of vibration in the downstream branch is higher than that in the upstream branch. Except for the upstream branch in the skewed double T-junction, the frequency is higher than that in a single T-junction. The fluid vibrations are closely associated with the fluid interference created by the presence of the two side branches.

Research on two-dimensional fluid vibration axial transmission path model of axial piston pump

High speed and high pressure can enhance the vibration of axial piston pump. A fluid vibration transmission law of axial piston pump is studied in this paper. According to harmonic response analysis results, a transmission path analysis is used to establish a two-dimensional fluid vibration transmission path model in the vertical plane, which has characteristics of multi excitation sources, multi-path and multi-receptors. Model parameters are obtained by experimental and numerical analysis. Matlab is used to solve the model, and acceleration vibration response of three shells is got. To reduce the effect of mechanical vibration, the surface acceleration of pump is tested under low speed condition. Results show that the model can accurately reveal transmission law of fluid vibration and the accuracy is more than 90%. The research lays a foundation for exploring vibration transmission law and vibration control.

Electrorheological Fluid and Its Application in Vibration Control

This paper deals with the application of electrorheological fluid (ERF) in shock absorbers. Such shock absorbers (ERF shock absorbers) whose damping force is controlled Continuously and promptly through electric singnals, can be used in many kinds of mechanical equipment for vibration control. Typical structures of ERF shock absorbers are described and requirements for the ERF employed in shock absorbers are discussed. A new kind of shock absorber and its control system are presented and test results of the ERF shock absorber are given.

Experimental investigation on control and reduction of vibration induced by fluid flow in turbine governing valve

Governing valve is the necessary passage through which steam enters into the steam turbine. The instability of the gas flow inside valve is the main reason that can induce the valve vibration, especially the valve rod vibration. In order to reduce the vibration and improve the performance of the governing valve such as the security and economy of the steam turbine, we try to find the method by experimental investigation. As to commonly used governing valve such as ball governing valve in this paper, a number of micro pressure sensors that have high frequencies and nice dynamic capability are employed successfully. The micro sensors are inserted directly in key positions of the valve, such as positions of valve seat throat, valve disc top and so on. The collection and measurement of many different working conditions are carried out and the conclusion of the valve instability is obtained. Therefore, vibration induced by fluid flow is controlled and reduced by means of regulating operation conditions and valve structure. Meanwhile, by numerical simulation of ball governing valve, valve disc adhered flow and asymmetric collision force are considered as main factor to cause oscillation under the condition of small lift as well as small and middle pressure ratio.

COMPLEX HEAT TRANSFER ENHANCEMENT BY FLUID INDUCED VIBRATION

A new method of heat transfer enhancement by fluid induced vibration was putforward, and its theoretical a-nalysis and experimental study were performed. Though people alwaystry to prophylaxis fluid induced vibration for regarding it as an accident, the utilization space offluid induced vibration is still very large. The in-surface and out-surface vibrations which comefrom the fluid induce elastic tube bundles, can effectively increase the convective heat transfercoefficient, and also decrease the fouling resistance, then increase the heat transfer coefficientremarkably.