Abstract

Improving fan design and performance prediction requires an understanding of the impacts of inlet distortions. Inlet distortion describes any non-uniform distribution in the flow, usually referring to deviations in pressure and temperature. Using full annulus Unsteady Reynolds-Averaged Navier Stokes (URANS) simulations, the effects of both hub and tip radial distortions on the Air Force Research Lab (AFRL) Rotor 4 fan are analyzed. Overall performance, total pressure (Pt) distortion transfer, and total temperature (Tt) distortion generation are presented and compared for three operating points: near-stall, design, and choke. Hub radial inlet distortion magnitudes of 15% and 20%, and a tip radial distortion of 15% magnitude were investigated. Comparisons to clean inlet simulations are provided for additional insight. The 15% hub radial profile increased stall margin by 18.45% compared with clean inlet. The 15% tip radial profile decreased stall margin by 89.47%. An intensity distortion descriptor is used to quantify levels of distortion transfer and generation through the fan. It is shown that hub radial profiles resulted in more significant Pt distortion attenuation and less Tt distortion generation through the rotor than the tip radial profile. Local rotor power decreases across all radial locations and operating points with an applied distorted inlet, but the effects are more significant with the applied hub radial distortion than tip radial distortion.

Degree

College and Department

Ira A. Fulton College of Engineering; Mechanical Engineering

Rights

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