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research-article

MODEL OF EFFECT OF HOT GAS INGRESS ON TEMPERATURES OF TURBINE DISCS

[+] Author and Article Information
J Michael Owen

Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK
j.m.owen@bath.ac.uk

Hui Tang

Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK
h.tang2@bath.ac.uk

Gary Lock

Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK
g.d.lock@bath.ac.uk

1Corresponding author.

ASME doi:10.1115/1.4040680 History: Received May 23, 2018; Revised June 18, 2018

Abstract

Ingress is the leakage of hot mainstream gas through the rim-seal clearance into the wheel-space between the rotating turbine disc (the rotor) and the adjacent stationary casing (the stator). The high-pressure (HP) rotor is purged by a radial outflow of air from the HP compressor, and this cooling air is also used to reduce ingress. The sealing effectiveness determines how much air is needed to reduce or prevent ingress; although there are numerous papers on the effectiveness of different seal geometries, there are few papers on the effect of ingress on the temperature of the rotating disc. This is an unsolved problem of great practical importance: under high stress, a small increase in metal temperature can significantly reduce operating life. In this paper, conservation equations and control volumes are used to develop theoretical equations for the exchange of mass, concentration and enthalpy in an adiabatic rotor-stator system when ingress occurs. A theoretical model has been developed to predict the relationship between the sealing effectiveness on the stator and the adiabatic effectiveness on the rotor, including the effects of both ingress and frictional heating. The analysis shows that the cooling flow acts as a buffer, which attenuates the effect of hot gas ingress on the rotor, but frictional heating reduces the buffer effect. The analysis quantifies the increase in the adiabatic rotor temperature due to direct frictional heating, which is separate from the increase due to the combined effects of the ingress and the indirect frictional heating.

Copyright (c) 2018 by ASME
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