Windage Heating of Air Passing Through Labyrinth Seals

Abstract

The viscous drag on rotating components in gas turbine engines represents both a direct loss of power from the cycle and an input of heat into the secondary (cooling) air system. Hotter cooling air in turn means increased flow requirements. The effects of windage on performance are therefore compounded. To facilitate accurate temperature predictions of highly stressed components, information is needed on windage characteristics of all elements in the secondary cooling system. Much information is available in the literature for disks, cones, cylinders, bolts, etc., but little has been published on windage heating in high-speed seals. Results are presented for experiments carried out (at representative nondimensional conditions) on different designs of labyrinth seals. The results are compared with values calculated from the simple momentum balance theory suggested by McGreeham and Ko [13] and with several values determined from CFD analysis.