Experimental Investigation of the Effect of a Novel Pea Jet Hole on Thermal Behavior of Jets Injected into a Crossflow

In film cooling, coolant air is injected over the surface to provide a protective cool film against the high temperature gases. Film-cooling performance is largely influenced by the jet hole shape. And thus optimizing the hole shape configuration is necessary to achieve better cooling performance. The present study investigated the cooling effectiveness of the novel incomplete cylindrical jet hole (pea jet hole) experimentally, using an infrared thermography method. Steady state heat transfer experiments were performed at free stream Reynolds number, based on jet hole diameter of 10,000, over a flat plate. Measurements were carried out at four blowing ratios (M=ρjetVjet/ρ∞V∞) of 0.4, 0.5, 0.7, and 0.8. Out results show that the novel pea jet hole has an optimum blowing ratio of 0.7 and at the same blowing ratio, in comparison to the cylindrical jet hole, the cooling effectiveness of the new geometry is higher. Another words applying the same amount of injected fluid, the coolout fluid is distributed more uniformly over the surface.