Influence of tip clearance and inlet flow distortion on ducted fan performance in VTOL UAVs

Ali Akturk, Cengiz Camci

Research output: Contribution to journalConference articlepeer-review

6 Scopus citations


Ducted fan vertical take-offand landing (VTOL) uninhabited aerial vehicles (UAV) are popular because they offer higher disk loading compared to open rotors and improve propulsive performance. Although ducted fans provide high performance in many VTOL applications, there are still unresolved problems associated with them especially in the forward flight mode. The main problems in these applications are distortion of inlet flow due to forward flight and tip leakage related problems in hover and forward flight modes. The present experimental study mainly uses total pressure measurements downstream of a ducted fan rotor to investigate the performance drop in hover and forward flight condition related with these problems. Tip leakage flow related total pressure losses are dominant in hover condition. Losses are dramatically increased in forward flight due to inlet lip separation and inlet flow distortion. For a better comparison of the tip clearance effects in forward flight, a new parameter named as "Forward flight penalty" is defined. In addition to comprehensive aerodynamic loss measurements downstream of the rotor, the paper also discusses the results from the early stage of a computational study aiming to calculate the 3D turbulent viscous flow in and around the ducted fan.

Original languageEnglish (US)
Pages (from-to)1443-1453
Number of pages11
JournalAnnual Forum Proceedings - AHS International
StatePublished - 2010
Event66th Forum of the American Helicopter Society: "Rising to New Heights in Vertical Lift Technology", AHS Forum 66 - Phoenix, AZ, United States
Duration: May 11 2010May 13 2010

All Science Journal Classification (ASJC) codes

  • General Engineering


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