Double-Ducted-Fan (DDF) as an Effective Lip Separation Control Concept for VTOL Vehicles

This paper describes a novel inlet flow conditioning concept that significantly improves ducted fans’ performance and controllability. High angle-of-attack operation of ducted fans is very common in vertical-takeoff-and-landing systems. The new concept named double-ducted fan (DDF) uses a secondary shroud to control inlet lip-separation-related momentum deficit at the inlet of the fan rotor during edgewise flight. The DDF is helpful in a wide edgewise flight velocity range, and its corrective aerodynamic effect becomes more pronounced with increasing flight velocity. A conventional baseline duct operating at 90 deg angle of attack is compared to other novel double-ducted fan designs via three-dimensional, viscous, and turbulent flow computations. A custom actuator-disk model replaces the zonal computation of the complex and three-dimensional rotor flowfield in the rotating frame of reference. Both hover and edgewise flight conditions are considered around the ducted fan unit and inside the ducts. Significant improvements from several novel ducted fan designs are in the areas of vertical thrust enhancement, nose-up pitching moment reduction, and recovery of fan through-flow mass flow rate in a wide horizontal flight range. A variable DDF design, a partial DDF design, and a fan-in-wing implementation of the DDF are introduced.



Work Title Double-Ducted-Fan (DDF) as an Effective Lip Separation Control Concept for VTOL Vehicles
Open Access
  1. Ali Akturk
  2. Cengiz Camci
License In Copyright (Rights Reserved)
Work Type Article
  1. American Institute of Aeronautics and Astronautics (AIAA)
Publication Date January 2022
Publisher Identifier (DOI)
  1. 10.2514/1.c036386
  1. Journal of Aircraft
Deposited February 23, 2022




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Work History

Version 1

  • Created
  • Added CCAA DDF separation-of-inlet-flow AIAA JA-1.pdf
  • Added Creator Ali Akturk
  • Added Creator Cengiz Camci
  • Published
  • Updated
  • Updated
  • Updated