Hot combustion gas in gas turbines can be ingested into the mid-passage gap between the blade platforms, resulting potentially a catastrophic damage. To prevent the ingress of hot gas, the blade platform underneath cavity is pressurized with purge air. Seals are typically installed in the mid-passage gap to minimize the purge air requirement. Under inadequate back flow margin, ingress of the main flow can occur especially at the upstream region of the mid-passage gap due to the pressure distribution characteristics on the platform. Excessive leakage flow can significantly reduce the turbine performance. This study investigated the effect of a seal installed in the mid-passage gap on film cooling effectiveness and heat transfer on the platform. Experiments were conducted by varying the ratio of the leakage flow to the main flow by 0.2%, 0.4%, and 0.6%, in which the mid-passage gap was unblocked (no seal; Opening 100% case) and partially blocked (seal; opening 50% case). The film cooling effectiveness of the platform was measured using the pressure sensitive paint method, and the heat/mass transfer coefficient of the platform was obtained using the naphthalene sublimation method. The seal in the mid-passage gap reduced or prevented completely the ingress of main flow under the given conditions. Under a high blowing ratio, the seal had little effect on the platform film cooling effectiveness. At the same mass flow rate of leakage flow, the heat transfer distributions were similar, regardless of whether a seal was installed. However, the platform with a partial seal in the opening 50% case showed a peak in the heat transfer closer to the gap than the platform without the seal, as the leakage flow reattached closer to the gap.

燃气轮机中的热燃气会被吸入叶片平台之间的通道中间间隙，从而可能造成灾难性的损害。为防止热气体进入，腔体下方的叶片平台被吹扫空气加压。密封件通常安装在通道中间间隙，以最大程度地减少吹扫空气的需求。在回流裕度不足的情况下，由于平台上的压力分布特性，特别是在中间通道间隙的上游区域，可能会发生主流的进入。过多的泄漏流量会大大降低涡轮机的性能。这项研究调查了安装在中间通道间隙中的密封件对薄膜冷却效率和平台上的热传递的影响。通过将泄漏流量与主流流量的比率分别更改为0.2％，0.4％和0来进行实验。6％，其中通道中间隙未阻塞（无密封；打开100％情况），部分阻塞（密封；打开50％情况）。使用压敏涂料法测量平台的膜冷却效率，并使用萘升华法获得平台的热/质量传递系数。在给定条件下，通道中间间隙的密封减少或完全阻止了主流的进入。在高吹塑比下，密封对平台膜的冷却效果影响很小。在相同质量流量的泄漏流下，无论是否安装密封件，传热分布都是相似的。但是，在开口为50％的情况下具有部分密封的平台比没有密封的平台显示出更靠近间隙的传热峰值，