Axial Compressor Response to Inlet Flow Distortions by a CFD Analysis

Abstract

The usual approach to compressor design considers uniform inlet flow characteristics. Especially in aircraft applications, the inlet flow is quite often non uniform, and this can result in severe performance degradation. The magnitude of this phenomenon is amplified in military engines due to the complexity of inlet duct configurations and the extreme flight conditions. CFD simulation is an innovative and powerful tool for studying inlet distortions and can bring this inside the very early phases of the design process. This project attempts to study the effects of inlet flow distortions in an axial flow compressor trying to minimize the use computer resources and computational time. The first stage of a low bypass ratio compressor has been analyzed and its clean and distorted performance compared outlining the principal changes due to uneven flow distribution: drop in mass flow, increase in pressure and temperature ratios, decrease in surge margin. Three different studies have then been conducted to better understand the effects of the level, the type and the frequency of the distortion.

Performance of a Low Speed Axial Compressor Rotor Blade Row under Different Inlet Distortions

“…Of researchers who have investigated on the effects of inlet flow distortions on axial flow compressor performance can be referred to Charalambous et al (2004). They showed that key signature of inlet distortion is drop in axial velocity magnitude within the distorted region.…”

Effects of Inflow Distortion due to Hub Cap's Shape on the Performance of Axial Flow Fan

“…It reveals that the strong swirl produced by the rotor causes the increase in loading of the compressor in the direction of rotor rotation through distorted region and the decrease in loading circumferentially away from the distorted region. Charalambous et al (8) also reviewed the effects of inlet flow distortions in an axial flow compressor by numerical simulation with k-ε turbulence model. They considered different kinds of inlet distortion: axial, radial, circumferential and mixed-type ones.…”