Numerical Study on Vibration Response and Fatigue Damage of Axial Compressor Blade Considering Aerodynamic Excitation

Xi Fu,Jiewei Lin,Junhong Zhang,Chao Ma

doi:10.3390/met11111835

Abstract

Axial compressor blades with a deformed initial torsion angle caused by aerodynamic excitation resonated at the working speed and changed the rule of fatigue damage accumulation. The fatigue life of a blade has a prediction error, even causing serious flight accidents if the effect of torque causing damage deterioration of the blade fatigue life is neglected. Therefore, in this paper, a uniaxial non-linear fatigue damage model was modified using the equivalent stress with torsional shear stress, and the proposed fatigue model including the torsional moment was used to study the compressor blade fatigue life. Then, the blade numerical simulation model was established to calculate the vibration characteristics under complex loads of airflow excitation and a rotating centrifugal force. Finally, the blade fatigue life under actual working conditions was predicted using the modified fatigue model. The results show that the interaction between centrifugal and aerodynamic loads affects the natural frequency, as the frequencies in modes dominated by bending deformation decreased whereas those dominated by torsional deformation increased. Furthermore, the blade root of the suction surface showed stress concentration, but there is an obvious difference of stress distribution and amplitude between the normal stress and the equivalent stress including torsional shear stress. The additional consideration of the torsional shear stress decreased the predicted fatigue life by 4.5%. The damage accumulation rate changes with the loading cycle, and it accelerates fast for the last 25% of the cycle, when the blade fracture may occur at any time. Thus, the aerodynamic excitation increased the safety factor of blade fatigue life prediction.

Highlights

The compressor blade is the core component of an aeroengine, which operates in an environment of high rotating speeds, high pressure, and high temperature
It is necessary to study the vibration characteristics and fatigue life predictions of a compressor blade considering aerodynamic excitation, which is of great significance to improving the reliability of aeroengines
Based on the theorical analysis, it was noted the fatigue damage behavior was greatly affected by the aerodynamic loads

Summary

Introduction

The compressor blade is the core component of an aeroengine, which operates in an environment of high rotating speeds, high pressure, and high temperature. With the improvement in the performance of aeroengines, the compressor loads are increasing. The high-speed rotating blades are subjected to centrifugal load by self-weight, but could be causing the vibration deformation with the initial twist angle, leading to the blade entering a complex stress state [4]. In this state, the blade can suffer fatigue failure under the coupling alternating loads, which is extremely harmful to the operational security of an aeroengine [5,6]. It is necessary to study the vibration characteristics and fatigue life predictions of a compressor blade considering aerodynamic excitation, which is of great significance to improving the reliability of aeroengines

Methods

Results

Conclusion