The theoretical methods used at ONERA for the blade-vortex interaction noise prediction are described. Prediction are performed in five steps: rotor trim, wake geometry, interacting vortices, blade pressure and radiated noise. Three ways of introducing the wake influence in unsteady load computations are investigated. The first one supposes that the tip filaments of the wake lattices are dominant. The second one treats all the filaments of the lattices as interacting vortices. The last one aims at modelling the local wake rolling-up and the vortex concentration. For each method, theoretical vortex geometries and intensities, loads, contour plots and acoustic signatures are presented and compared to experiment. They show the benefit of using a roll-up model in blade vortex interaction noise computation. Indeed, the tip filament assumption appears not general enough for realistic applications and the whole lattice approach does not seem reliable. On the contrary, fairly good aeroacoustic results are achieved using the roll-up modell. Particularly, this modelling allows to deal with rotor geometries and kinematics which are likely to generate inboard vortices.
Improvement of helicopter rotor blade-vortex interaction noise prediction using a rotor wake roll-up model
Verbesserte Vorhersage des Rotorflügel/Wirbelstrom-Wechselwirkungsgeräusches mit dem Rotor-Nachlaufturbulenz Roll-up-Modell
1995
9 Seiten, 16 Bilder, 12 Quellen
Conference paper
English
British Library Conference Proceedings | 1995
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