The Analysis Of Fluid-structure Interaction In Pipelines Of Aircraft Hydraulic System

As the power source of the aircraft flight control system and landing gear loads, aircraft hydraulic system plays a key role for the safety of aircraft flying. The pulse flow output of the Aircraft hydraulic system pump forced vibration and resonance in the fluid-conveying pipe. If the pump pulse frequency closes to the natural frequency of the pipe, it will produce a fluid-solid interaction (FSI) resonance. FSI vibration will cause the reduced life of piping and hydraulic components, pipe support structure damaging, serious pipe wall rupture, support stiffness dropping, piping system failure and hydraulic oil leak, and then results in a serious catastrophic accidents. Therefore, it is very important to clarify the aircraft hydraulic system piping FSI vibration mechanism so as to design a new safe and reliable hydraulic system and the vibration suppression measures of existing aircraft hydraulic systems.In this paper, the piping FSI vibration mechanism of the aircraft hydraulic system is analyzed. The research work involves several aspects as follows:1) Analyze the piping FSI vibration mechanism of the aircraft hydraulic system, discuss and summarize the aircraft hydraulic system piping layout and the general law of FSI. Analysis shows that a gradual decline in pipeline supporting structure stiffness characteristics of the slow-varying parameters is real reason for the damage and failure of the aircraft hydraulic system pipelines and related supporting structure.2) Summarize and develop the linear differential equations of the derivation of the fluid and pipe movement, established the dynamic equations and the finite element equations of aircraft hydraulic system piping FSI vibration. As can be seen, the effect of FSI is achieved by the interaction of the fluid and the structure of the piping.3) Based on the FSI dynamic equations of pipe flow and the finite element equations, use the finite element software ANSYS to simulate and analyze FSI vibration of straight pipe flow. The simulation example shows that the different pipe supporting clips,different pipe length and different fluid flow speed greatly impact the pipeline vibration, pipe structural design shall be based on different circumstances choose a suitable support structure, pipe type and suitable pitch between adjecent supporting clips.