Some experiments on the propagation of sound along a cylindrical duct containing flowing air

Abstract This paper gives the results of an experimental study of the propagation of sound along the cylindrical working section of a wind tunnel. The effect of fluid flow on the modal cut-off frequencies was investigated and rather complete details of the various methods of detecting the frequencies are given because of the lack of any such description in the literature. The cut-off frequencies were found to decrease in frequency with increasing flow speed for sound propagation both up and down stream.