Heat Transfer Investigation Of Film Cooling On The Leading Edge Of Turbine Blade

The efficiency of gas turbine engine is increased with increasing inlet gas temperature of turbine component. The gas temperature at inlet of turbine is about 1900K for modern aero-engines. It is much higher than the melting temperature of the heat resisting metal which widely applied in the manufacture of turbine blade. Therefore the design skill of cooling technique becomes one of the key in development of advanced new engines. The leading edge region of airfoil has the highest heat transfer rate over the entire airfoil. Typically, the coolant from within the airfoil is injected through several lows of the discrete holes around lead edge region to protect the surface and reduce heat transfer rate. In order to get better understanding of film cooling characteristic on leading edge, investigation program was carried out in Heat Transfer Laboratory of Northwestern Polytechnical University in Xi'an China.Measurements were conducted in a closed-looped wind tunnel. The model has a semi-cylinder leading edge with a diameter of 75 mm and a height of 500 mm. At ± 90° from the stagnation line, the leading edge profile merged with 500 mm long flat walls. The tail part is designed as semi-ellipse to reduce the aerodynamic loss. The test model is made of Plexiglas with a thickness of 22.5 mm. Mainstream flow velocity and the Reynolds number based on the leading edge diameter are about 10 m/s and 45000, respectively. The mass flux of secondary flow was measured by using a float meter located at the upstream of electrical heater. A row of 7 holes starts 2 hole-diameters from the stagnation line measured on the perimeter of the circle. Detailed numerical simulations on the three-dimensional N-S equation solver turbulent flow and heat transfer were carried out with one row injection on the leading edge. The characteristics of the flow and temperature fields, including the coolafit trajectory,the heat transfer and the complicated distribution of adiabatic effectiveness in the region of leading edge are all expounded.