Numerical Analysis on the Effect of J-groove on Flows in Narrow Gaps between Rotating Disk and Casing

Abstract

During operation and working of turbo machines, axial thrust balancing is important. To control and balance the axial thrust, a very simple method using shallow radial grooves mounted on the casing wall, called “J-groove”, was proposed, and studied experimentally[1]. This paper presents a numerical study of the effect of J-groove on the flow in the narrow gap along enclosed rotating disks based on open-source CFD software. It is seen that the difference in pressure between the hub and shroud tip is increased with the increasing number, depth, and length of J-groove. But in the case of increasing width of J-groove, the pressure loss along the radius decreases when the ratio of the groove width to the outer radius W is less than 0.2 and increases when W greater than 0.2.