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THERMAL MODELLING OF HEAT TRANSFER IN A ROTATING DISC DUE TO A SUPERPOSED FLOW OF COOLING AIR

DOI: 10.1615/IHTC13.p22.420
page 11

D. Zhang
Chinese Academy of Sciences, Beijing, China

S. Varah
Now at ConocoPhillips, North Lincs, UK

G. D. Lock
University of Bath, Bath, UK

Michael Wilson
Department of Mechanical Engineering University of Bath Bath BA2 7AY United Kingdom

Abstract

Temperature variations around the cooling air receiver holes in gas turbine rotor discs may give rise to large thermal stresses around the edges of the holes, and so cause fatigue that could affect component life. In the present work, a finite element thermal model is used to simulate a simplified cooling air delivery system that has previously been studied experimentally. In these experiments, heated air flowed over a plane rotating disc made from transparent polycarbonate and painted with thermochromic liquid crystal (TLC), and heat transfer coefficients were deduced using the surface temperature information recorded by the TLC and a one-dimensional transient analysis technique. These measured heat transfer coefficients have been used here to supply boundary conditions to the finite element model, which is found to reproduce qualitatively the temperature changes with time observed experimentally. The validity of the one-dimensional assumptions made in the analysis of the experiments is also demonstrated.
The model is then adapted to study conditions representative of those occurring in engines, by scaling the measured heat transfer coefficients to typical engine operating conditions using a correlation based on rotational Reynolds number. These results show significant variations in the temperature of the disc around the receiver holes. Finally, the same boundary conditions are mapped to the surface of a generic 3D geometry representative of a turbine disc in an engine. The computed temperature distributions agree with information derived from other sources, suggesting that the detailed results from the simplified experiments should be useful to designers of gas turbine engines. The regions of highest thermal stress occur around the receiver holes and contribute to an estimated fatigue life for the simulated turbine rotor of around 15,000 hours.

IHTC-13 Digital Library

Measurement of fluid temperature with an arrangement of three thermocouples FLOW BOILING OF A HIGHLY VISCOUS POLYMER SOLUTION