Author： Polacsek Cyril Zibi Joe¨lle Rouzaud Olivier Kuntz Martin
Publisher： AHS International
ISSN： 2161-6027
Source： Journal of the American Helicopter Society, Vol.44, Iss.2, 1999-04, pp. : 121-131
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Abstract
Euler/Kirchhoff methods have been developed at ONERA and DLR to predict the High Speed Impulsive (HSI) noise generated by helicopter rotors in hover or in forward night. The main purpose of this common work is to validate and to compare aeroacoustic computations on delocalized test cases. Code to code comparisons show rather close aerodynamic and acoustic predictions. Acoustic results are identical when using the same aerodynamic inputs. In hover, both aerodynamic and acoustic results obtained by each partner are in good agreement with experiment. In forward flight, a first set of computations relative to a non-rectangular blade rotor model is performed using three different sized grids. Correlation of blade pressure coefficients improve experiment when the grid is refined. However, the capture of the shock waves beyond the blade is not accurate enough to get reasonable noise predictions with respect to the Kirchhoff surface location, whatever the grid refinement may be. In order to improve the aeroacoustic computations in the far-field, an “adapted“ grid has been generated. Acoustic predictions are clearly improved, showing the requirement for a grid adaptation to perform accurate HSI noise predictions on advanced blade geometries.
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