Title: Conjugate Heat Transfer Predictions of Effusion Cooling: The Influence of the Coolant Jet-Flow Direction on the Cooling Effectiveness
Abstract: Effusion cooling of a flat wall was investigated using conjugate heat transfer CFD. The main variable investigated was the angle of the coolant jets relative to the crossflow. Experimental data for the overall cooling effectiveness using a metal effusion cooled wall was modelled for an X/D of 4.65, coolant to crossflow density ratio of 2.56, ten rows of holes in the crossflow direction and a blowing ratio M of 0.2–3.27 or mass flow per surface area, G, of 0.088–1.47 kg/sm2. The experimental data for 90° normal injection was modelled and then the influence of injecting each effusion hole 30° downstream and 150° downstream (or 30° upstream) was predicted. The coupled thermal mixing between the hot-gas and coolant jets and the heat transfer within the effusion walls were modelled using the ANSYS FLUENT code. The computational results of the overall cooling effectiveness of the validation case was of the order of about 8–12% less than the experimental data but the trend of the results was well predicted. A methane tracer gas was added to the coolant air and this enabled the adiabatic cooling effectiveness to be predicted as well as the overall cooling effectiveness. At high blowing ratios, the co-flow inclined and normal jets were characterised with kidney-shaped pair vortices which degrade the adiabatic film cooling effectiveness. The counteraction of the fluid dynamics between the oppose-flow jets and hot-gas momentum prevents the formation of the kidney-shaped pair vortices with the usage of opposed-flow wall. The oppose-flow jet was shown to be the best effusion cooling design with the greatest transverse spread of the film cooling at high blowing ratios. This was an unexpected result that has very few previous studies. The results show that significant reductions in coolant mass flow rate for the same wall temperature could be achieved or lower wall temperatures for the same coolant mass flow.
Publication Year: 2012
Publication Date: 2012-06-11
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 21
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