Forced response analysis of compressor blades under unsteady inlet distortion

Aircraft maneuver in high angle of attack can cause severe unsteady inlet distortion, which may induce forced response of compressor blades. Research on blade forced response is premise and basis for high-cycle fatigue life analysis. A compressor rotor blade is investigated with three-dimensional numerical simulation in fluid-structure coupling methods. Total pressure wake of inlet unsteady distortion is assumed as a sinusoidal function as parameters of turbulence intensity and excitation frequency. Different turbulence intensities and excitation frequencies are discussed in forced response analysis of rotor blades. The result demonstrates that turbulence intensity above 4% enhances the blade vibration level significantly. At 71.75% rotation speed, blade forced response is typically excited by dynamic total pressure distortion in 667Hz frequency, which is close to natural frequency of second flexural mode. Unsteady total pressure distortion induces increment of deformation and stress fluctuation. Although turbulence intensity and structure damping ratio are same compared with 667Hz, blade forced response level decreases and mechanical vibration energy of blade system is consumed by structure and aerodynamic damping in 286Hz excitation frequency. Inlet unsteady distortion in first to fourth engine order frequency does not induce significant forced response of compressor blades.