Third M.I.T. Conference on Computational Fluid and Solid Mechanics June 14–17, 2005  

Assessment of simulation techniques for rotor loads prediction

R. Steijl*, G. Barakos, K. Badcock
CFD Laboratory, Department of Aerospace Engineering, University of Glasgow, Glasgow G12 8QQ, UK

  Full Text
Numerical simulation of hovering rotor cases has been undertaken using computational fluid dynamics (CFD) as well as reduced aerodynamic models in an attempt to identify the advantages and disadvantages of each method. A wellknown test case has been identified corresponding to the experiments of Caradonna and Tung on a Mach scaled rotor. On the CFD front, the Euler's equations have been used in conjunction with the control volume method. The reduced model was based on the indicial approach and coupled with a prescribed wake model. The obtained results indicate that prediction of the rotor loads is possible using CFD despite the lack of resolution in the wake region. Grids of up to 3 million points per blade were used on average, each calculation required about 12 hours on a 10-node Beowulf cluster. Although the prescribed wake model was much faster than CFD, it was found to be sensitive to the 'tuning' parameters of the wake and consequently its range of application is restricted. Present results indicate that CFD methods can reliably predict the loads of the rotor but the lack of resolution at the wake restricts their routine application to the rotor design task. Problems like rotor/fuselage or main-rotor/tail-rotor interaction are still too expensive to be computed routinely.

Keywords:  Hovering rotors; Rotorcraft CFD; Rotor wake; Indicial methods; Rotor loads

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