Study of Trailing-Edge Cooling Using Pressure Sensitive Paint Technique

An experimental investigation was conducted to study the effects of blowing ratio and the existence of lands on the film cooling effectiveness of a turbine blade trailing-edge model. Instead of using a temperature-based technique, a mass transfer analogy was used to quantify the film cooling effectiveness. This was done through the measurement of the distribution of oxygen concentration over the surface of interest with airflow as the mainstream flow and nitrogen as the coolant stream. The pressure sensitive paint technique was used to map the distribution of the oxygen concentration on the surface of the cutback region of the trailing-edge model. The experimental study was conducted at five different blowing ratios between 0.4 and 1.6, both with and without moveable lands mounted on the trailing. edge model. The measurement results indicate clearly that the blowing ratio and the existence of the lands would affect the film cooling effectiveness of the tailing-edge design significantly. The detailed film cooling effectiveness maps were correlated with the characteristics of the flow structures revealed from the particle image velocimetry measurements to elucidate underlying physics and to explore and optimize design paradigms for a better protection of the critical portions of turbine blades from the extremely hot environment.