Heat transfer in a trailing cooling channel using ejection slot with different chordwise length ratio of impingement cavity

Impingement cooling is conducive to enhancing the cooling performance of turbine blade trailing edge channel, and slot ejection can be adopted for additional cooling. This paper explores the influence of the chordwise length ratio of the impingement cavity to the ejection slot on the channel’s heat transfer and friction factor. In the experiment, three models with the chordwise length ratios (CR) of 1.6, 0.68, and 0.36 were tested under the Reynolds number of 22,000–69000. The flow field was numerically simulated when CR = 0.68. The distribution of Nusselt number on the pressure and suction sides of impingement cavity and ejection slot was obtained. Besides, the heat transfer distribution mechanism was explained based on the flow characteristics obtained through numerical study. Through evaluation of the overall heat transfer and pressure loss of each structure, it can be observed that chordwise length ratio constitutes an important factor for heat transfer. It was found that the overall Nusselt number is larger when CR is smaller, but there is a limit to the enhancement of heat transfer performance. Among the three models, the structure with CR = 0.68 suffers the maximum pressure loss. In conclusion, the cooling performance could be improved, with less pressure loss, by optimizing the chordwise length ratio of the impingement cavity to the ejection slot.