Abstract
Correlations using a loosely coupled trim methodology of the computational fluid dynamics (OVERFLOW-2) and computational structural dynamics (CAMRAD-II) codes are presented to calculate the helicopter rotor blade-vortex interaction airloads and wake system for the higher-harmonic aeroacoustic rotor test (HART II) rotor at an advance ratio of 0.15. Five different grid models are studied to quantify the effects of grid refinement on rotor-wake resolution. The fine grid model has a total of 113 million grid points and it improves airload predictions compared with the standard grid model for three HART II test cases: baseline, minimum noise, and minimum vibration. The rotor-wake positions are well predicted by this fine grid model. The computed vorticity field for a young vortex using the fine grid model is compared with the measured particle image velocimetry data and the results are good. The fine grid model underpredicts the experimental value for the maximum vorticity by 61%. The predicted vortex core radius is Is % in chord for the fine grid while the measured data show about 5% chord length. The predicted swirl velocity is, however, higher than the measured data for this vortex. The results in this paper provide the first quantitative comparisons between the measured and computational fluid dynamics/computational structural dynamics computed flowfield for a helicopter rotor-wake system.
Published Version
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