Abstract
Sound generated by hydraulic jump has been investigated experimentally and theoretically. The process of sound scattering from hydraulic jump is so complex that the system has not yet been studied in detail. Mainly four origins of the sound were considered in the present paper, i. e., oscillations of a single bubble, bubble cloud, sound occurred during the breakup of free surface and the resonance of an air column. To reveal the origin of the spectral peaks appeared in the power spectrum of sound data, we measured the sound at various locations along the hydraulic jump. Also, to specify the origin, salt and cleaning-material were mixed into the working water in order to change the void fraction of hydraulic jump.Furthermore, to investigate more clearly the relation between each physical process and the spectral peaks of sound, the experiment of free fall of a round jet into a still water-tank was also achieved for various jet velocities and different depths of water-tank.
We have concluded that the strong peak of the spectrum occurs from bubble cloud oscillations, but the other peaks are originated from the generation of bubbles and the existence of air columns at the free surface.
