Abstract
A swirl motion of a liquid jet has high mixing ability and it is useful for wastewater treatment. Water model experiments have been carried out to understand the occurrence condition and basic characteristics of a swirl motion of a wastewater jet generated by a J-shaped lance in a cylindrical vessel. As the water injected into the vessel is not circulated with a pump, the bath depth increases continuously with a lapse of time. In the initial stage of water injection the water jet rises straight upward. When the bath depth exceeds a certain critical value, the jet oscillates in the radial direction. With a further increase in the bath depth, two types of swirl motions appear: shallow-water and deep-water wave types. The period and amplitude of the swirl motion of deep-water wave type are measured with a high-speed video camera.
