椭球形凹陷 / 凸起通道流动和传热特性研究

The development of high-efficiency and low-resistance internal cooling structures is of great significance for the efficient cooling design of turbine blades of gas turbine engines. In this paper, the flow characteristics and heat transfer performance of oval dimples / protrusions in the rectangular channels are numerically investigated for Reynolds numbers between 10 000 and 60 000,the depth-to-diameter ratio (h / D) of the oval dimples was 0.25, and the blocking ratio (h / H) of the protrusions ranged from 0.18 to 0.25. The influence of the type, arrangement, and distance between dimples / protrusions on the flow resistance and average heat transfer characteristics as well as the thermal-hydraulic performance in the channel, was analyzed. The simulation results show that flow reattachment occurs at the leading edge of the oval protrusions, the downstream trailing zone, and the trailing edge of the oval dimples, so that the high heat transfer zones of the oval protrusions are located at its leading edge as well as in the downstream trailing zone, and the high heat transfer zones of the oval dimples are located at the trailing edge boundary. The V-arranged oval protrusions exhibit the best heat transfer performance, with the thermal-hydraulic performance and relative averaged Nusselt numbers decreasing with increasing Reynolds number, and the relative friction factor increasing with increasing Reynolds numbers. The thermal-hydraulic performance of the V-arranged oval protrusions is 20% ~ 40% higher than that of the flat plate, the averaged Nusselt numbers is 55% ~ 73% higher than that of the flat plate, and the friction factor is about twice as high as that of the flat plate. When the distance is decreased, the area of the high heat transfer zones of the oval dimples / protrusions increases, the area of the low heat transfer zones decreases, and the thermal-hydraulic performance increases.