Session: 14-02 Rotating Cavities

Submission Number: 177133

Entrainment of Swirled Axial Throughflow in a Rotating Compressor Cavity Under Centrifugal Buoyancy-Driven Convection 

Future jet engine compressors are expected to feature overall pressure ratios (OPR) that exceed 70:1. The core of compressor will downsize with higher OPR, increasing the importance of managing blade-tip clearance. This clearance is influenced by compressor rotor expansion, which is dictated by the flow structure and heat transfer inside the cavities between co-rotating discs. This unstable flow structure is induced by buoyancy under centrifugal acceleration at high Grashof number. Further, the flow is destabilised by the enthalpy and momentum exchange with an axial throughflow of cooler air at low radius. The throughflow forms part of the secondary air system and inherently features swirl from rotating components within the compressor. In some cases, the swirl (relative to the rotating discs) can exceed unity. This paper presents an experimental study of the influence entrained fluid to the rotating compressor cavity over a range of Rossby number and axial-throughflow swirl. The University of Bath Compressor Cavity Rig was used to measure the radial distribution of air temperature in the throughflow and entry to the compressor cavity, the radial distribution of temperature on the discs inside the cavity, the shroud heat flux, and the resultant flow structure from unsteady pressure. Correlations for shroud Nusselt and Grashof numbers are linked to swirl and the radial mass flow within the buoyancy-induced structures forming in the cavity.

Presenting Author: Sebastian Syncerz University of Bath

Presenting Author Biography: Sebastian is a PhD student at the University of Bath

Authors:

Sebastian Syncerz University of Bath
Dominic Lafone-Ward University of Bath
Mai Mohamed University of Bath
Hui Tang University of Bath
Gary Lock University of Bath
James Scobie University of Bath