Research On Fluid- Structure Interaction Of Hydraulic System Pipes Based On Numerical Analysis

Pipeline systems are widely used in water electrical, mechanical chemical,aerospace, marine engineering, hydraulic system, urban water supplying and drainaging and all other fields. Hydraulic system pipeline is as a typical conveying- fluid system, the fluid-structure interaction vibration problem with pressure flow in a pipe in this area is highly representative of the research direction, it has a broad background of engineering applications, but also faces many challenging problems.In paper, firstly, numerical solution method of partial differential equation and partial differential equations were introduced, grid difference scheme, first-order upwind difference scheme, difference scheme of the method of characteristics's structure and adwantage of the method characteristic were included, and the solution method of ordinary differential equa- tion that after transformation was given, Those which lay a foundation for numerical simulation of hydraulic system pipeline vibration response.The prediction step of numerical simulation of mechanical pipeline vibration was taken as giudance, and hydranlic system pipeline as the research object, first-order upwind difference scheme and the method of characteristic were used to transform the four equation modle of pipeline axial vibration. The simulation modle which was convennient for numerical processing was got, the validity of the algorithm was proved by comparing between the numerical results and those of test from literature. Pipeline was divided equally to make sinulation which according to minimal wave speed, the vibration response of liquid pressure and pipeline internal force was analyzed, and the vibration response characteristics of hydranlic system pipeline axial was obtained.The effect of pipeline structure parameters on vibration response was studied, the longer of the pipeline, the more obvious of the pipeline vibration response; Liquid friction damping has obvious attenuation effect on pipeline vibration; Pipeline structure damping plays a minor role on decaying the fluid pressure and internal force of hydraulic system system, but it has more attenuation effect on pipeline velocity; With pipeline wall thickness increasing, the pipeline internal force changes little, liquid pressure energy is increased, the pipeline energy is reduced; With pipeline diameter increasing, the pipeline internal force changes little, pipeline vibration energy is increased, the liquid vibration energy is decreased; When pipeline material as copper and steel, the pipeline internal force respond is larger and vibration energy is concentrated in the liquid, when uses PE pipepipe, pipeline internal forces response is small and the vibration energy is concentrated in the pipeline. Those provide guidance for researching pipeline damping and pipeline system design.MOC-FFT method was used to research and analysis the hydraulic system pipeline natural frequency. First the MOC method was used to obtain the hydraulic system pipeline response in time domain, and then FFT method was used to analysis and obtain the natural frequency characteristics of hydraulic system pipeline vibration. The result of calculation is in good agreement with that of the experiment.