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CFD Study of a New Annular Lift Fan Configuration with High Lift Efficiency

by Yun Jiang * and Bo Zhang
UAV Research Institute, Northwestern Polytechnical University, 127 West Youyi Road, Xi’an 710072, China
*
Author to whom correspondence should be addressed.
Academic Editor: Robert Spall
Aerospace 2017, 4(1), 13; https://doi.org/10.3390/aerospace4010013
Received: 2 February 2017 / Revised: 25 February 2017 / Accepted: 27 February 2017 / Published: 3 March 2017
A new annular lift fan configuration that has very high lift efficiency is explored by using a numerical scheme. The inlet lip radius and diffuser angle are maximized by semicircle duct walls and the location of the lift fan is moved from the throat to the diffuser area to maximize the diffusion effect of the ducted fan. The improved lift fan achieves the figure of merit of 0.772 and the power loading of 9.03 lbs/hp without ground effect, very close to the theoretical limit. Under the ground effect, the figure of merit reaches 0.822 with the power loading of 9.62 lbs/hp. The improved lift efficiency deteriorates the transition characteristics with higher momentum drag and pitching moment. However, with the aid of jet thrusts directly providing part of the lift during transition, the peak of momentum drag and pitching moment can be lowered. A total thrust to weight ratio of 0.7 is enough for all of the requirements in transition and in hover and for the maximum speed of 0.75 Mach in cruise flight. View Full-Text
Keywords: lift fan; VTOL; ducted fan; lift efficiency; transition; annular; aircraft lift fan; VTOL; ducted fan; lift efficiency; transition; annular; aircraft
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MDPI and ACS Style

Jiang, Y.; Zhang, B. CFD Study of a New Annular Lift Fan Configuration with High Lift Efficiency. Aerospace 2017, 4, 13.

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