Research On Vibration Characteristic And Life Prediction Of Compressor Blade Based On Fluid-Structure Coupling Method

Aeroengines provide power for the operation of aircrafts.As a key component of aero-engine rotor system,the service life and reliability of high-pressure compressor blades are one of the key factors for the safe operation of airliners.The high-speed rotating compressor blades are subject to centrifugal,aerodynamic and other complex loads.Under the complex alternating load,the blades are prone to occur unsteady vibration that lead to the fatigue failure.Considering the coupling effect between air flow and blade structure,it is very important to analyze the vibration characteristics and strength of high pressure compressor blade,which is of great scientific significance and engineering application value for the operation safety and optimization design of aeroengine.In this paper,the vibration characteristics of high-pressure compressor blades are analyzed based on the fluid-solid coupling method,and the fatigue life prediction is carried out.The main contents are as follows:The three-dimensional model of the five-stage rotor blade and its fluid domain were established,and the solid models were divided into meshes.According to the actual operation of the aero-engine,six kinds of typical speed conditions were determined.Based on the theory of fluid-solid coupling,the fluid-solid coupling model was established.The fluid flow software ANSYS Fluent was used to simulate the flow condition of the compressor to obtain the aerodynamic load on the blade at the corresponding speed.Secondly,the vibration characteristics of the blades under centrifugal and aerodynamic loads were analyzed,and the natural frequencies and corresponding modes of the blades were obtained.The effects of different fluid-solid coupling modes on the vibration characteristics of the blade were studied.The effects of different modes on the vibration frequency were analyzed.Thirdly,the unsteady aerodynamic loads were introduced into the transient dynamic response of the compressor blades.The variation law and the distribution law of the transient stress of the blades were summarized and the dangerous points of the blades are determined,which lays the foundation for predicting the fatigue life of the blades.According to the structural dynamic equation,the variation law of the blade deformation was analyzed and the displacement response of the blade under different working conditions was studied.Finally,in order to improve the reliability of the prediction results of blade life,three kinds of blade models with different precision were established.The stress distribution of the compressor blades under complex loads was taken into account in consideration of centrifugal and aerodynamic loads.The load changes for different dangerous points of different modeling schemes were compared.The operating state of the civil aviation engine was classified into five working cycles.And the life expectancy of the three blade models was predicted by the S-N curve life prediction model.