Post stall propeller behavior at low Reynolds numbers

Daniel V. Uhlig, Michael S. Selig

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


A framework for efficient flow solution around rotors in forward flight by transforming governing flow equations to multiblade coordinate system (MCS) is presented. Solution method is based in the frequency domain to take advantage of the inherent periodicity of the flow. The summation process inherent in transformation of governing flow equations to MCS leads to cancellation of many harmonics. Fewer time locations around the azimuth are required to accurately calculate the remaining harmonics. This leads to an increase in efficiency and decrease in required memory compared to traditional frequency domain solution based in single global rotor coordinate system (RCS). Dynamic structured grid in the rotor domain is generated using a simple and efficient transfinite interpolation method. Distributed plus multithreaded programming technique is implemented to parallelize portions of the code which can be executed simultaneously and manage the memory requirements. Results are obtained for rotors with multiple blades with NACA0012 profile for non-lifting and various lifting forward flight cases. Solutions for these cases are compared with experimental results and RCS based results with excellent agreement. Conventional frequency domain method based in RCS was proved to be an order of magnitude faster compared to time domain method in earlier studies. The efficiency of current frequency domain method based in MCS is found to be higher than RCS based method by a factor approximately equal to the number of blades. Thus frequency domain CFD in multiblade coordinates shows great potential for obtaining accurate and efficient helicopter rotor flow prediction.

Original languageEnglish (US)
Title of host publication46th AIAA Aerospace Sciences Meeting and Exhibit
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
ISBN (Print)9781563479373
StatePublished - 2008

Publication series

Name46th AIAA Aerospace Sciences Meeting and Exhibit

ASJC Scopus subject areas

  • Aerospace Engineering


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