| Autor: |
Thorsten Lutz, Ewald Kraemer, Werner Wuerz, Andreas Herrig |
| Rok vydání: |
2006 |
| Předmět: |
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| Zdroj: |
24th AIAA Applied Aerodynamics Conference. |
| Popis: |
This paper describes a hot-wire based method for two-dimensional trailing edge noise measurements mainly for use in wind tunnels with high background noise levels. The method is based on the cross correlation of two hot-wire signals, allowing to measure the Coherent Particle Velocity (CPV) of the emitted sound waves. The strong directional sensitivity of the hot-wires leads to a suppression of parasitic noise, which significantly improves the signal-to-noise ratio. Due to the small dimensions of the sensors together with the assured laminar flow condition they are well suited for inflow measurements. To obtain quantitative results in terms of sound pressure level, the sensitivity of the measurement setup is derived by simulation of the response of the hot-wires to a line source. For validation, trailing edge noise measurements were performed at 60m/s and a Reynolds number of 1.6×10 in the closed test section of the Laminar Wind Tunnel Stuttgart (LWT), using the CPV-method. Finally, the same airfoils were investigated in the open jet of the Aeroacoustic Wind Tunnel Braunschweig (AWB) using a phased microphone array. The quantitative comparison of the experimental results obtained in the two wind tunnels required the application of appropriate wind tunnel corrections. The obtained sound pressure frequency spectra are basically found to be parallel in the frequency range of sufficient measurement accuracy. The total sound pressure levels vs. lift coefficient show a more or less constant offset of about 2 dB between AWB and LWT. Given the totally different measurement principles this can be regarded as a good agreement. Finally results of a NACA 0012 airfoil are presented and compared to published data. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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