Comparison of adiabatic and conjugate heat transfer models on near-wall region flows and thermal characteristics of angled effusion cooling holes

Abstract

This paper aims to evaluate the accuracy and efficiency of different numerical simulation approaches on cooling performance for the angled effusion cooling holes applied in a micro gas turbine (MGT) combustor liner. The geometric structure processing methods of a 3-D multi-perforated plate are performed for conjugate heat transfer (CHT) and adiabatic models. Numerical approaches are verified by experimental data in terms of centerline film cooling effectiveness. The wall cooling film effectiveness, film thickness and discharge coefficient of the multi-perforated plate are studied and discussed under the condition of whether there is solid heat conduction. Results show that the adiabatic model cannot predict the veritable wall cooling effectiveness distribution on the inner wall surface and overestimates the discharge coefficient by nearly 16.5%. However, the accuracy of the adiabatic model in predicting the near wall flow field structure is not lower than that of the CHT model. Both of the two model can predict a film thickness of 4.1 mm at the same sampling position. Further studies indicate that the increases of flow direction β have a significant impact on the improvement of wall cooling effectiveness distribution in the spanwise direction. The Ux magnitude predicated by adiabatic model is increasingly close to that of CHT model. The predication results also illustrate a relatively fixed difference of 0.1 between these two models.