    Effective cooling structure design in the trailing edge (TE) of a high pressure turbine (HPT) blade is essential to increase turbine efficiency and maintain structural integrity. To obtain efficient trailing cooling structures and understand clearly cooling mechanism, this paper adopted numerical simulation methods to investigate fluid flow and cooling characteristics in detail downstream of a HPT blade TE cutback region. The effects of typical TE configurations on cutback cooling performance are investigated including three types of internal turbulators (cylindrical pin fins and elliptic pin fins arranged in spanwise and streamwise orientations), the cutback with/without land extensions and three kinds of ejection lip profiles (one straight and two rounded shapes). The Scale Adaptive Simulation (SAS) model is implemented to study the complex unsteady mixing process downstream of the cutbacks under operating condition of blowing ratio M=0.65. The results from the Shear Stress Transport (SST) k-ω model are compared as well.

    The SAS model is capable to reproduce the periodical vortex shedding phenomena and resolve the vortices coherent structures. Compared with the experimental data, the SAS model provides more accurate predictions in terms of laterally averaged adiabatic cooling effectiveness η~aw~ and discharge coefficient C~d~ than the SST k-ω. On the rear part of the cutback surface, large deterioration in η~aw~ is predicted by the SAS model for all configurations, but η~aw~ is considerably over-predicted by the SST k-ω model except for the case with elliptic pin fins in spanwise orientation. The elliptic pin fins with streamwise orientation significantly improve η~aw~ at the rear part of the cutback surface over the baseline model with cylindrical pin fins and slightly increase C~d~. However, the elliptic pin fins with spanwise orientation drastically reduce the η~aw~ and C~d~. Downstream of the trailing edge, the coherent structures are strongly disturbed and become chaotic compared to the TE with cylindrical and streamwise oriented elliptic pin fins. The application of land extensions only causes an evident change to the coherent structure immediate downstream of the lip, and slightly improves η~aw~ and reduces C~d~ over the baseline model on the rear part of the cutback surface. Rounded lip shapes B and C also show an obvious increase in η~aw~ on the rear part of the cutback surface but only a minor increase in C~d~ compared to the straight lip shape A. The rounded lip helps the coolant to diffuse into to the TE of the lip and reduce the intensity of mixing. Due to larger rounding radius of shape B, the cooling effectiveness predicted by shape B is slightly better than shape C.


Application of Scale Adaptive Simulation Model to Studying Cooling Characteristics of a High Pressure Turbine Blade Cutback Trailing Edge With Different Cooling Configurations

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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