Trailing-Edge Noise Measurements Using a Hot-Wire Based Coherent Particle Velocity Method

This study focuses on the acoustic installation effects that may occur during typical aeroacoustic experiments when the latter are conducted in a closed-vein wind tunnel. More precisely, in regard to the specific problem of airfoil trailing edge noise, an analytical model is derived, which allows predicting the wall-induced reverberation effects that such a noise shall be subjected to, when radiating within a closed-vein, hard-wall, wind tunnel. These effects are then assessed through a parametric investigation so as to characterize their impact on in situ acoustic measurements that would be performed using flush-mounted microphones located on the vein’s walls. From a phenomenological perspective, the study highlights how important the reverberation effects by the vein can be. In particular, results reveal how their impact on the noise measurements may greatly vary, depending on the trailing edge noise source location (i.e., the airfoil incidence) and, to a lesser extent, its frequency. The outcomes allow identifying these locations where the installation effects are least, i.e., where to better position a flush-mounted microphone, should in situ noise measurements be conducted. From a methodological viewpoint, the study showcases how the proposed formalism could constitute a simple albeit useful diagnosis tool for mitigating the experimental biases weighing on airfoil trailing edge noise tests to be conducted within closed-vein facilities, whether this would be done a priori by flush-mounting the microphone(s) where these biases are minimal or a posteriori by de-biasing the noise measurements accordingly.

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Airfoil trailing edge noise measurements with a directional microphone

10.2514/6.1977-1269 ◽

1977 ◽

Cited By ~ 11

Author(s):

R. SCHLINKER

Keyword(s):

Trailing Edge ◽

Trailing Edge Noise ◽

Directional Microphone ◽

Noise Measurements

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Computation of trailing-edge noise due to turbulent flow over an airfoil

AIAA Journal ◽

10.2514/3.15312 ◽

2002 ◽

Vol 40 ◽

pp. 2206-2216 ◽

Cited By ~ 4

Author(s):

A. Oberai ◽

F. Roknaldin ◽

T. J. R. Hughes

Keyword(s):

Turbulent Flow ◽

Trailing Edge ◽

Trailing Edge Noise

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Withdrawal: SAS-based Airfoil Trailing Edge Noise Prediction in Stall Conditions

AIAA AVIATION 2020 FORUM ◽

10.2514/6.2020-2744.c1 ◽

2020 ◽

Author(s):

Yuejun Shi ◽

Denghui Qin

Keyword(s):

Noise Prediction ◽

Trailing Edge ◽

Trailing Edge Noise

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Noise source location and scaling of subsonic upper-surface blowing

International Journal of Aeroacoustics ◽

10.1177/1475472x20930652 ◽

2020 ◽

Vol 19 (3-5) ◽

pp. 191-206

Author(s):

Trae L Jennette ◽

Krish K Ahuja

Keyword(s):

Strouhal Number ◽

Noise Source ◽

Low Frequency ◽

Directivity Pattern ◽

Source Location ◽

Dipole Source ◽

Frequency Noise ◽

Noise Sources ◽

Trailing Edge ◽

Trailing Edge Noise

This paper deals with the topic of upper surface blowing noise. Using a model-scale rectangular nozzle of an aspect ratio of 10 and a sharp trailing edge, detailed noise contours were acquired with and without a subsonic jet blowing over a flat surface to determine the noise source location as a function of frequency. Additionally, velocity scaling of the upper surface blowing noise was carried out. It was found that the upper surface blowing increases the noise significantly. This is a result of both the trailing edge noise and turbulence downstream of the trailing edge, referred to as wake noise in the paper. It was found that low-frequency noise with a peak Strouhal number of 0.02 originates from the trailing edge whereas the high-frequency noise with the peak in the vicinity of Strouhal number of 0.2 originates near the nozzle exit. Low frequency (low Strouhal number) follows a velocity scaling corresponding to a dipole source where as the high Strouhal numbers as quadrupole sources. The culmination of these two effects is a cardioid-shaped directivity pattern. On the shielded side, the most dominant noise sources were at the trailing edge and in the near wake. The trailing edge mounting geometry also created anomalous acoustic diffraction indicating that not only is the geometry of the edge itself important, but also all geometry near the trailing edge.

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