| The aero-engine is one of the most important components of the aircraft,fuel,oil,hydraulic oil,etc.are equivalent to the blood of the engine,are mainly transported through the external piping system.The importance of the structural and functional integrity of the piping system to the continued airworthiness of the aero-engine is selfevident.Due to the installation,welding,the vibration of the basic environment and the interaction between the pipeline and the foundation,the pipeline and the transport medium,the pipeline system is more prone to vibration failure,and the pipeline unsafe problem induced by the vibration factor has become One of the main factors that can cause negligence in aero-engine system failure.Firstly,the configuration and structural characteristics of the external pipeline system of civil aircraft engine are analyzed and summarized,combining main factors of vibration of external pipeline of engine,taking stainless steel straight pipe and concave pipe as examples,then the pipeline vibration modal experiments with block clamp and elastic clamp support constraints as boundary conditions are designed and carried out.The impact hammer and resistance strain gauge are used as excitation input and response pick-up units respectively.In addition,the experimental modal analysis of concave pipe is carried out with the length of the elbow as variable parameter.The results show that the odd first and third natural frequencies of concave pipe under two kinds of constraints are negatively correlated with the length of the elbow,and the even second and fourth natural frequencies are positively correlated with the length of the elbow.The first and second natural frequencies change more slowly,and the third and fourth natural frequencies change more quickly,and increase or decrease in more rapidly trend.Using UG NX and ANSYS Workbench software,modeling and modal simulation of the straight and concave pipes are carried out.The comparison between simulation and test results shows that the first three fixing frequencies of the pipes under block clamp support are greatly increased compared with those under elastic clamp support,which is helpful to improve the resonance zone of the pipes when the engine works.At the same time,through harmonic response analysis,the resonance zone of the pipes is obtained.The vibration response characteristics of the pipeline under unbalanced fixed frequency and sweep frequency excitation of the engine rotor provide a reference for improving the resonance of the pipeline in the actual work of the engine.The research on vibration modal experiment of aeroengine exterior pipeline and the in-depth analysis of pipeline harmonic response are helpful to better understand the vibration of engine pipeline when working,and provide a new idea and method for preventing and solving the vibration problem of aeroengine exterior pipeline. |
