Strong unsteady broadband perturbations are found in a tip clearance flow and related to acoustic radiation using standard techniques as well as advanced cross-wavelet analysis. The experiment is carried out on a single non-rotating airfoil in the anechoic wind tunnel facility of the Ecole Centrale de Lyon. The airfoil is placed between two plates into a Mach 0.2 openjet flow. A strong leakage flow is obtained with a high lift, 5 % camber airfoil at a 15 deg angle of attack. The leakage flow occurs in an adjustable gap between the lower plate and the airfoil tip and the sound radiated into the cross-stream direction is measured in a medium at rest. The influence of the gap size is investigated. PIV measurements are carried out both around the airfoil and in the gap region providing a detailed view of the flow. Unsteady pressure measurements on the airfoil, both in the mid-span region and in the gap region, are combined with single HWA and PIV measurements. A special care is given to placing the probes on the tip of the airfoil, the tip edges and the plate facing the tip. Moreover, 2 sets of probes are installed in the mid-span region both spanwise and chordwise near the trailing edge. An advanced wavelet analysis of the pressure fields allows to identifying the aeroacoustic sources and to relate them to turbulent eddies generated in the gap region.
Aeroacoustic investigation of a tip clearance flow
2007
8 Seiten, 8 Bilder, 15 Quellen
(nicht paginiert)
Conference paper
Storage medium
English
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