Flow through Narrow Clearance between Rotating Cylinder and Stationary Wall

Abstract

It is important to estimate the leakage flow rate through a rotor clearance of positive-displacement type fluid machine and flowmeter. In order to :make clear the flow through the top clearance between the lobe rotor and the easing wall not only in laminar regime but also in turbulent regime, experiments are carried out by using a model passage composed of a rotating cylinder and a stationary straight wall. In the laminar regime, the leakage flow rate through the top clearance is estimated theoretically. When the cylinder is at rest, the transition from laminar to turbulent flows occurs at Reynolds number Re=150 based on the minimum clearance and the mean velocity in it. The effect of the rotating direction and speed on the critical Reynolds number is also discussed. In the turbulent regime, the empirical equation for the leakage flow rate is obtained.