Gas turbine performance largely depends on the inlet temperature. Higher the inlet temperature better is
the performance of the turbine which in turn may adversely affect the turbine blades. Film cooling techniques
are used to protect the turbine from hot gases. In this study, secondary holes were added to the
compound angle holes to improve the turbine performance by enhancing the film cooling. Four blowing
ratios were considered in this study. A Baseline case with zero orientation angle and 30 inclination angle
was used as a reference. To analyze the film cooling effectiveness with reference to the Baseline case, four
different cases (cases with 30 and 60 orientation angles with and without secondary holes) were studied.
Thermocouples and infrared camera were used to study the effectiveness of the film cooling. Infrared
camera shows its ability to capture the temperature variation in a finite area due to its high resolution.
The results show that the cases with compound angle have higher effectiveness compared to the Baseline
case. Also, providing secondary holes helps keep the main hole jet to move beside the test surface and
results in higher effectiveness especially at high blowing ratios. |
