Lip separation and inlet flow distortion control in ducted fans used in VTOL systems

Ali Akturk, Cengiz Camci

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Scopus citations

Abstract

This paper describes a novel ducted fan inlet flow conditioning concept that will significantly improve the performance and controllability of ducted fan systems operating at high angle of attack. High angle of attack operation of ducted fans is very common in VTOL (vertical take off and landing) UAV systems. The new concept that will significantly reduce the inlet lip separation related performance penalties in the edgewise/forward flight zone is named DOUBLE DUCTED FAN (DDF). The current concept uses a secondary stationary duct system to control inlet lip separation related momentum deficit at the inlet of the fan rotor occurring at elevated edgewise flight velocities. The DDF is self-adjusting in a wide edgewise flight velocity range and its corrective aerodynamic effect becomes more pronounced with increasing flight velocity due to its inherent design properties. Most axial flow fans are designed for an axial inlet flow with zero or minimal inlet flow distortion. The DDF concept is proven to be an effective way of dealing with inlet flow distortions occurring near the lip section of any axial flow fan system, especially at high angle of attack. In this present paper, a conventional baseline duct without any lip separation control feature is compared to two different double ducted fans named DDF CASE-A and DDF CASE-B via 3D, viscous and turbulent flow computational analysis. Both hover and edgewise flight conditions are considered. Significant relative improvements from DDF CASEA and DDF CASE-B are in the areas of vertical force (thrust) enhancement, nose-up pitching moment control and recovery of fan through-flow mass flow rate in a wide horizontal flight range.

Original languageEnglish (US)
Title of host publicationAircraft Engine; Fans and Blowers
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791845578
DOIs
StatePublished - Jan 1 2014
EventASME Turbo Expo 2014: Turbine Technical Conference and Exposition, GT 2014 - Dusseldorf, Germany
Duration: Jun 16 2014Jun 20 2014

Publication series

NameProceedings of the ASME Turbo Expo
Volume1A

Other

OtherASME Turbo Expo 2014: Turbine Technical Conference and Exposition, GT 2014
Country/TerritoryGermany
CityDusseldorf
Period6/16/146/20/14

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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