Ms. Torok et Cr. Berezin, AERODYNAMIC AND WAKE METHODOLOGY EVALUATION USING MODEL UH-60A EXPERIMENTAL-DATA, Journal of the American Helicopter Society, 39(2), 1994, pp. 21-29
An evaluation of several aerodynamic methodologies; lifting line, lift
ing surface and CFD, and wake methodologies; vortex lattice and consta
nt vorticity contour models, is made to determine their applicability
and validity in the prediction of helicopter airloads. Integrated blad
e loads, blade pressures and blade strain data taken on a model UH-60A
BLACK HAWK rotor are utilized to assess the capabilities of the aerod
ynamic analyses. Prescribed torsional deformations, derived from test
data, are used to create a uniform basis from which to compare the met
hods. Test conditions chosen for this study include a high speed trans
onic flow condition, a low speed, highly distorted wake condition, and
a descending flight, blade-vortex interaction(BVI) condition. Results
, in general, show good agreement between predicted and measured blade
loads. Both 2-D and 3-D unsteady aerodynamic models show improvement
over a quasi-steady model, with the 3-D Full Potential method (FPR) yi
elding the best predictions in the blade tip region. Three wake models
, UTRC's FREEWAKE, CDI's RotorCRAFT, and Johnson's dual-peak, modified
Scully model perform comparably, all having difficulties in predictin
g the complex vortex flow in the first quadrant. The FPR analysis yiel
ds good predictions of chordwise pressure distributions. For the BVI c
ondition, the inclusion of a discrete vortex segment within the comput
ational domain of FPR yields a significantly improved BVI pulse predic
tion. This translates to a largely improved BVI acoustic prediction.