Analysis of Radial Inlet Distortion on Transonic Fan Performance

Abstract Improving fan design and performance prediction requires an understanding of the impacts of inlet distortion. Using full-annulus unsteady Reynolds-averaged Navier–Stokes (URANS) simulations, the effects of hub and tip radial distortions on the Air Force Research Laboratory (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. Results from twelve simulations are presented and analyzed. Hub radial inlet distortion magnitudes of 15% and 20%, and a tip radial distortion of 15% magnitude were investigated. The 15% hub radial profile increased stall margin by 18.45% compared with the clean inlet. The 15% tip radial profile decreased the 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.