In this paper, a predictor-corrector with 2nd-order backward difference (PC2B) time accurate free wake algorithm with explicit modification is formulated to investigate the rotor unsteady aerodynamic characteristics.As the rotor free wake equation possesses the characteristics of non-linearity, its solutions are susceptible to numerical instability.The modified equation of a different format is derived to investigate the accuracy and the numerical stability of the modified PC2B algorithm, and the stability and calculation efficiency of the algorithm are verified by a numerical experiment.Based on the algorithm, the rotor aerodynamic characteristics are first calculated and the validation of the rotor free wake model is performed with the experimental data for hover and ramp up in collective pitch.Secondly, the rotor unsteady aerodynamic characteristics are investigated during the collective pitch maneuver phase.Results demonstrate that the fluctuation of the rotor unsteady aerodynamic characteristics during the collective pitch maneuver phase stems from the transient variation of the rotor free wake geometry.
LIU Yong
,
SHAO Song
,
ZHU Qinghua
,
ZHANG Chenglin
. Analysis of Rotor Unsteady Aerodynamic Characteristics Based on Time Accurate Free Wake Formulation[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2012
, (4)
: 607
-616
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DOI: CNKI:11-1929/V.20120201.0943.008
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