Behaviour of Two-Dimensional Water Jets Sensitive to Sound

Effects of Applied Sound on Velocity Profiles

Abstract

The effects of sound on air jets have been studied by many researchers, but the behaviour of two-dimensional water jets sensitive to sound, which is especially important for the application of fluidics in oceanography, has not yet been clarified.
In this study, the authors investigated experimentally the fundamental behaviour of a two-dimensional water jet affected by sound, to find out the exact jet-sound relationships. The jet profile variables including the centerline velocity, the jet width, and the velocity distribution of the jet were measured with a hot film anemometer. Especially, the tendency of the velocity distribution of the jet was compared with Görtler's model.
The following facts were confirmed:
1) A water jet becomes sound-sensitive when both its Reynolds number and the frequency of sound are within some bounds.
2) When a sound of certain frequency is applied, the jet centerline velocity increases but the velocity in the outer shear layer decreases. In this case, a sound-sensitive jet has a responsive frequency bandwidth involving the maximum value of centerline velocities which shifts towards a higher frequency with an increase in the Reynolds number.
3) The tendency of the spread parameter shows that such changes in the velocity profile with the application of sound are related to the abrupt spreading of the jet following the transition from a laminar domain to a turbulent domain.