The Fluid And Structure Interaction Vibration Characteristic Research Of Piston Pumpand Pipeline

Hydraulic transmission technology is a kind of liquid as the medium. It is also an industrial technology use the liquid pressure to deliver power. In the vast majority of hydraulic systems, the pump is the "core" of power component. At present, the development trend of hydraulic system of equipment: large,automation, high pressure flow quantitative. This trend will inevitably lead to the following phenomenon: the distance between actuator(hydraulic cylinder)and hydraulic source is more and more far. Especially the long pipeline which exists between valve and actuator. The long-term practice has proved that under high pressure, large flow rate working environment, the vibration problem which is caused by the fluid-structure coupling in the hydraulic system will become increasingly prominent. Therefore, the research of vibration problem which is caused by fluid-structure coupling has a big engineering application value and practical significance.This article analyses the vibration signal which is acquired from hydraulic system. Then combining with the mechanics of materials, fluid mechanics and finite element analysis method to analyze the hydraulic system. This paper obtain the vibration characteristic which is caused by different reason. And put forward some feasible suggestions which is used to reduce the vibration noise in the hydraulic system. The main work is as follows:1. Deduce the axial piston pump fluid-structure interaction problems theory.Axial piston pump is fluid-structure coupling mechanical equipment. Itsvibration characteristic is very complicated when working. This article uses the characteristic line- fast Fourier transform method(MOC- FFT) in the plunger pump to study the vibration characteristics which is caused by fluid-structure coupling. Through the method of characteristic line, this paper solve fluid-solid coupling vibration partial differential equation and get the time domain signals.Then according the fast Fourier transform method, the natural frequencies of the piping system can be obtained. According to we study of vibration characteristics in the frequency domain, this paper obtained the frequency which the type of A10 V pump should be avoided when working. And we get change regularity of the angle of swash plate, pressure and the speed of rotation how to affect the high frequency vibration spectrum which is caused by the FSI.2. Liquid pipeline fluid-structure coupling kinematics theory. According to Hamilton principle, using the method of finite element and mechanics of elasticity, this paper deduce the straight pipe three-dimensional vibration equation which is consideration of fluid-solid coupling problem. On this basis,we use the discretization model to modeling of bent pipe and make the bending pipe to discrete into infinite straight pipe section. According to the continuity equation and momentum equation, the node boundary conditions can be determined. Thus bent pipe three-dimensional vibration equation which is consideration of fluid-solid coupling is obtain. Then this paper got finite element model of pipe and provided basis for studying the power flow in liquid-filled pipeline. In this part,we completed the kinematics analysis of the pipeline.3. The dynamics of liquid pipeline theoretical derivation. Fluid-structure interaction problem is caused by fluid incentive the pipeline. Therefore from the transmitting dynamics research of incentive fluid, this paper got the pressure wave speed which is existed in the fluid. By draw an analogy with circuit components, we obtain the transfer equation of fluid pressure pulsation. From it,we have the relationship between flow rate and pressure. On this basis, we canstudy the effect of fluid dynamic parameters on the fluid pressure pulsation. By means of calculation, this paper studied how the phase of fluid pressure pulsation to effect the vibration of pipe, then we got some feasible suggestions to reduce the vibration.4. Simulation of fluid-solid coupling problems. Through the software of ANSYS, we make the wet modal simulation of long pipeline. Firstly, 3d model of long pipeline is established by SOLIDWORKS, then we import the model into FLUENT software to simulate for turbulent flow in pipe flow. After this, we import the pressure result into statics module(static structural), eventually is to make prestressed modal analysis. By observing the former five order modal frequency and modal vibration mode to compare pipeline optimization result. It is verified the correctness of the pipeline optimization theory.5. Experimental verification of fluid-solid coupling problem. Setting up the experimental platform: inverterâ†'motorâ†'the axial plunger pumpâ†'pipelineâ†'overflow valveâ†'lineâ†'tank. Because the plunger pump and pipeline between the overflow valve and actuator is the main vibration source of hydraulic circuits,we set KISTLER three-axial accelerometer on the pump body which is near the inclined plate to monitor the pump vibration. We install a three-axis accelerometer at the overflow valve to monitor the excitation frequency of pipeline which between the overflow valve and actuator(hydraulic cylinder).According to the analysis of experimental collection data, it is verified the correctness of the theoretical derivation.