Experimental study of the effect of swirling inflow on film cooling effectiveness

Lean burn combustor can save fuel and reduce pollutant emissions. The exit of the lean burn combustor generates strong swirling flow, which has a significant influence on the heat transfer performance of the downstream turbine. Turbine cooling systems have been designed under uniform inflow in the past, lean burn combustor pose new challenges to the design of cooling systems for downstream turbines. In this paper, the effect of swirling inflow on the film cooling effectiveness on the pressure and suction sides of the turbine was experimentally investigated, and the performance of the cylindrical film hole and water-drop shaped hole and fan shaped hole were compared. The results show that the swirling inflow makes the distribution of film uneven and reduces the average value. The swirling inflow reduces the area averaged cooling effectiveness by 5.5% under design working condition. The expanded film hole can improve the cooling effectiveness under swirling inflow. On the suction side, the fan shaped hole performs better than the water-drop shaped hole. On the pressure side, the water-drop shaped hole performs better than the fan-shaped hole. As for area averaged value, the water-drop shaped hole and fan shaped hole perform 46.6% and 51.5% improvement, respectively, compared with cylindrical hole under design working condition.