Experimental and Numerical Study of Twin Circular Water Jets Impinging on a Moving Thin Film

Abstract

In this study, we investigated the flow characteristics of two circular water jets impinging on a moving surface covered with a water film as fundamental research on strip cooling. Experiments and numerical simulations were conducted under non-heated surface conditions. The experiments were recorded on video. The jet velocity, nozzle-to-plate distance, nozzle-to-nozzle spacing, and flow rates of the water film were varied systematically. Depending on the flow conditions, three types of flows were found to exist between the two modes: stable, unstable, and transient. We propose a simple theoretical model for predicting the critical boundary at which the flow is in the “stable mode.” In the numerical simulation, the Navier–Stokes equation system for a three-dimensional incompressible unstable viscous fluid was solved using a finite difference method. The effects of viscosity, gravity, and presence of a free liquid surface with surface tension were considered. The flow characteristics of the “unstable mode” are discussed in detail to offer a better understanding of its physics.