Experimental investigation of film cooling from two staggered rows holes,backward and forward; of opposite injection angles has been done. The forward holes row was embedded in arc trench. The aim of using arc trench is to enhance the poor mechanical properties of that in rectangular trench. The results of film cooling performance are given here in a form of adiabatic cooling film effectiveness and heat
transfer coefficients. In the tests test warm air is blown through tunnel, and cold air through the plenum chamber. When the warm air flowed through the test section it heated the model downstream. Infrared camera is used to measure the model surface temperatures. The comparison with the same holes arrangements and same holes and trench dimensions between existing rectangular trench results and present arc trenched
showed that the film cooling thermal performance for both cases are approximately very close with slight differences, these differences are more or less according to the values of blowing ratios.