Flow in a Narrow Gap Along an Enclosed Rotating disk with Through-Flow

Abstract

Flow in a narrow gap along an enclosed rotating disk superimposed with through-flow is studied theoretically and experimentally. When the axial gap is narrow, or a large outward through-flow is imposed, the boundary layers on the rotating and the stationary walls interfere with each other. The present study proposes an analytical model for such interference of gap flow and gives a theoretical analysis which is easily applicable to various boundary conditions. For non-interference of gap flow, a theory giving better results than conventional theories is also presented and the critical gap between these two flow patterns is determined theoretically. It is shown that the radial pressure distribution is dependent mainly upon wall shear stress and radial expansion of the sectional area in the case of gap interference, and on the centrifugal force of the core flow in the case of gap non-interference. The coefficient of the disk friction moment is shown to be proportional to Re^-1/4 in the case of gap interference, and to be Re^-1/5 in the case of gap non-interference.