Numerical Analysis of the Effect of Natural Convection Heat Transfer on the Gas Turbine Axial Compressor Casing

Document Type : Research Article

Authors

1 Research of Department of Compressor/ Turbotec Company, Tehran, Iran

2 Head of aerodynamic department/ Turbotec Company, Tehran, Iran

3 Head of Department of Compressor/ Turbotec Company, Tehran, Iran

4 CEO/ Turbotec Company, Tehran, Iran

Abstract

The distortion of the turbine casing in response to changes in pressure and temperature conditions takes place due to various reasons. Casing distortion decreases the efficiency by increasing the flow loss at the tip of blades and seals of the turbine. In this study, the effect of natural convection heat transfer on the compressor’s casing in gas turbine was investigated. For this purpose, the fluid  and solid domains were simultaneously and transiently analyzed by numerical method while applying different boundary conditions to a two-dimensional model. The results showed that due to natural convection, the temperature of the upper parts of the casing increased up to a certain time and then faced a fluctuating decrease, while the temperature of the lower parts generally decreases over time. Natural convection causes a considerable temperature difference in the casing at shutdown conditions. Also, flow turbulence in the fluid is high due to the high Rayleigh Number. Although the Rayleigh Number increases as the environment’s convection transfer coefficient raises, the temperature gradient between the upper and lower casing decreases locally. To reduce the casing distortion, practical solutions of adjusting the environment’s convection transfer coefficient, changing the logic of bleed valves, and improving casing insulation have been proposed.

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References

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Amirkabir Journal of Mechanical Engineering
Volume 52, Issue 4
July 2020
Pages 797-812

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