Flow Characteristics of Circular Liquid Jet Impinging on a Moving Surface Covered with a Water Film

The flow characteristics of a single circular water jet impinging on a moving surface covered with a water film have been investigated by means of experiments and three-dimensional computer simulations. The experiments were conducted by varying the jet velocity, nozzle-to-plate distance, and flow rate of the water film. It was found that the following three types of flow structures existed: an almost steady flow structure, an unsteady flow structure, and a transition flow structure between the steady and the unsteady flows. The critical boundary, at which the almost steady flow structure appears, is discussed using a simple potential flow theory. In the numerical simulation, the liquid flow was assumed to obey the Navier-Stokes equation in the three-dimensional Cartesian coordinate system. The effects of viscosity, gravity, and the presence of a free liquid surface were taken into account. The predictions were in reasonable agreement with the experimental results. Each flow structure has been studied in detail for a better understanding of the physics of the phenomena.