Numerical And Experimental Research For Full Coverage Film Cooling

In order to satisfy the flame tube and turbine blade cooling requirements which come from the improving aeroenginee performance, highly efficient cooling methods develop quickly. Full coverage film cooling is a widespread concerned and practical cooling method today. Its main feature is that the cooling wall is intense with discrete cooling holes,so it can form film coverage well on the film side and a more effective convective heat transfer inside film cooling holes.So this paper will have a more deeply research on full coverage film cooling.The convective heat transfer characteristics inside film cooling hole were investigated numerically and experimentally. The effects of Reynolds number, film cooling hole angle and length-diameter ratio on the heat transfer inside the film cooling hole were revealed. Results show that: (1) The convective heat transfer coefficients are enhanced with increasing Reynolds number. (2) Increasing the hole angle enhances the convective heat transfer near the entrance to a film cooling hole. (3) The circumference average heat transfer coefficient decreases monotonously along film hole length, the total average convective heat transfer coefficient inside the film cooling hole is higher under little length-diameter ratio.The full coverage film cooling characteristics were investigated numerically and experimentally. The effects of the blowing ratio, the film holes array arrangement, hole diameter and deflected angle on film cooling effectiveness, convective heat transfer coefficient on the cold side and film side, discharge coefficient of the full coverage discrete holes wall were concluded. Results show that: (1) As the blowing ratio increases, the total cooling effectiveness and the adiabatic wall cooling effectiveness increases in the same wall position.(2)The convective heat transfer coefficient on the film side increases along the flow direction;for the cold side,as the cold flow is heated along the flow direction, the convective heat transfer coefficient decreases. (3) As the blowing ratio increases, the convective heat transfer coefficient on the cold side and film side increases.(4) The film holes array arrangement has little impact on convective heat transfer coefficient on the cold side and film side.(5)In the same holes area percentage, the smaller the hole diameter is ,the higher the cooling efficiency is.(6)The eflected angle improves the lateral uniformity of the film coverage and increases the cooling efficiency,the total cooling effectiveness and the adiabatic wall cooling effectiveness also increases as the eflected angle increases. (7) The discharge coefficient increases as the blowing ratio increases, but decreases as the eflected angle increases.