Studies of the Developing Flow Between Concentric Cylinders With the Inner Cylinder Rotating

Abstract

The present paper is part of the third phase of an investigation of the phenomena and variables which control the rate of heat transfer in the air gap of a rotating electrical machine. Experimental studies were made in the developing adiabatic flow of air in an annulus having a rotating inner cylinder and stationary outer cylinder. Experiments were made to determine when Taylor vortices, and/or turbulence occurred as a function of Reynolds number of the flow; rotational speed of the inner cylinder; and distance from the inlet. Lines of demarcation of the several modes of flow were established for positions along the axis of the annulus. Two length effects were present: the distance to the point where vortices occurred and the distance required for the vortices to develop. A criterion is presented for determining the point in a developing flow where Taylor vortices originate. The value is given in terms of the dimensionless parameter, ωr1δb*νδθ*r1>24. A discussion of the occurrence of vortices in well-developed flows is presented.