Measurement analysis of aerodynamic noise in low speed wind tunnel

Measurement of aerodynamic noise generated by a body in the airflow or the turbulent flow itself is crucial for today’s aerodynamic development. For accurate acoustic measurement of aerodynamic noise generated by surfaces in the airflow special facility is usually required. This paper analyzes an approach for measuring base integral characteristics of aerodynamic noise (sound pressure levels) generated by a body in the airflow inside the section of the low speed wind tunnel. Initially the noise generated by the wind tunnel, its driving unit and the ambient noise were considered. The noise generated by the wind tunnel is not only of the aerodynamic nature, but for some operating conditions the magnetic noise is the most dominant part of the sound emissions. From this point of view the measurement requirement and limitations were further considered. In the second part of this analysis an anechoic chamber around the open test section of the wind tunnel was built. Inside this anechoic chamber three ¼” microphones were mounted. The measurement of the sound pressure levels at the specific points in the anechoic chamber was performed. The results of this measurement were evaluated and discussed the further usage of this approach to the aerodynamic generated noise measurement.