Aa. Hassan et al., A CONSISTENT APPROACH FOR MODELING THE AERODYNAMICS OF SELF-GENERATEDROTOR BLADE-VORTEX INTERACTIONS, Journal of the American Helicopter Society, 41(2), 1996, pp. 74-84
A numerical procedure has been developed far the prediction of the thr
ee-dimensional unsteady aerodynamic response of a helicopter rotor dur
ing self-generated blade-vortex interactions (BVI), Pertinent vortex w
ake parameters (e.g,, spatial and temporal trajectories, strengths) we
re computed using the lifting-line rotor/helicopter trim code CAMRAD/J
A, In this code, tracking of the near-field BVI vortex-wake segments w
as accomplished using a new ''box'' technique which involves tracking
all tip vortex elements tying inside a user specified box-like domain
which encloses the rotor, Unsteady blade surface pressures were then p
redicted using a modified version (designated FPRBVI) of the full pote
ntial rotor code FPR (v2,1), Two approaches were used to model vortex-
induced effects in the FPRBVI solver; the efficient surface or ''trans
piration'' approach, and the more comprehensive split potential approa
ch, The numerical procedure was used to predict the unsteady aerodynam
ic response of the one-seventh scale two-bladed AH-IG OLS model rotor
and a United Technologies Corporation 17.5% scale four-bladed model ro
tor during self-generated BVI, Accuracy of the numerical procedure was
assessed using wind tunnel data.