Experimental Investigation of the Influence of Aerodynamic Loading on the Transmission Loss Through Kevlar Membranes

Kevlar walled wind tunnels have become widely used for aeroacoustic testing. Our research documents that a pressure difference across the Kevlar membrane influences the transmission of sound through it. Such effects have been ignored up to the present day which might lead to inaccurate results when testing objects that generate large aerodynamic forces. An experiment to document the effects of aerodynamic loading on the transmission loss factor of sound through the Kevlar membrane was conducted. An analytical correction scheme to compensate for it was developed. The bias in the sound pressure level measurements out side the test section that is introduced by bias flow through the Kevlar membrane was compensated by applying the analytical model.