Propagation study of distorted flow along rotor blades and its impact on blade vibration

Abstract

Inlet distortion can reduce the compressor’s stability margin and, in severe cases, lead to blade flutter. However, the mechanisms how inlet distortion, after being mitigated by Inlet Guide Vanes (IGV), affects the vibration characteristics of rotor blades (R1) remain unclear. To address this issue, the present study constructs an integrated model of the inlet duct and the compressor. Initially, using Particle Image Velocimetry (PIV) technology and Computational Fluid Dynamics (CFD) simulations, the study quantitatively characterizes swirl distortion and total pressure distortion at the outlet of the inlet duct. Subsequently, it explores how distorted inflow propagates along the rotor blades, revealing that the low-speed wake generated by the distortion and the tangential flow at the blade tip acts as excitation sources for R1 vibration. Finally, distortion suppression strategies are explored from the perspective of mitigating these excitation sources. The research findings indicate that combined distortion alters the force acting on the blades around their circumference. Significant variations in the flow state on the blade’s suction surface lead to differing vibration amplitudes. Specifically, the lowest tip amplitude increases by 68 μm compared to the case with uniform inlet flow, while the highest tip amplitude rises by 296 μm. Adjusting IGV angle forward effectively suppresses swirl distortion. When β = 10°, ζ is minimized, resulting in an efficiency increase from 88.6% to 91%. Changes in the structural parameters significantly impact DC60, where increasing both c and D₀ leads to a rise in DC60. Considering both R1 efficiency and ζ, the I-1 group proves to be optimal.