Recent studies have demonstrated that the simple cylindrical hole with backward injection, where the jets are injected reverse to the mainstream flow direction, outperforms its forward-injected counterpart at relative high blowing ratios. Meanwhile, trench is known to be of high cooling effectiveness with forward injection at high blowing ratios. Few studies addressed the combination of the two setups. The present study investigated the simple and trenched cylindrical hole configurations with either forward or backward injection by experiments. The injection angle was 30° and 150° for the forward and backward setup separately. The trench had a depth of 0.75D and the trench width was 1D and 2D. Adiabatic effectiveness was measured with PSP, and heat transfer augmentation was obtained with transient method using the IR camera. Detailed distributions were obtained. Blowing ratio was varied from 0.25 to 4.0. The density ratio was 1.0 or 1.5 in PSP measurements, and was 1.0 only for the heat transfer measurements. For the simple cylindrical hole with backward injection, the result confirmed the advantage of it at high blowing ratios, and also showed that its adiabatic effectiveness is highly uniform in the spanwise direction. Meanwhile, the backward-injected configuration had a much more stable cooling performance as the VR varied. It was further pointed out that the flow field of the simple backward-injected case is governed by the recirculated region downstream the hole exit. The narrow trench enhanced the effectiveness hugely along with forward injection, while the enhancement to the simple backward injection was quite limited. Moreover, the narrow trench performed far better than the wide trench. It was revealed that the key of the mechanism depends on the interaction of the jet with the downstream trench wall.

最近的研究表明，具有反向喷射的简单圆柱孔，其中射流以与主流流​​动方向相反的方向喷射，在相对高的吹气比下优于其正向喷射的对应物。同时，众所周知，沟槽在高吹气比下具有前向喷射的高冷却效率。很少有研究涉及两种设置的组合。本研究通过实验研究了具有向前或向后注入的简单和沟槽圆柱形孔配置。向前和向后设置的注射角度分别为 30° 和 150°。沟槽深度为 0.75D，沟槽宽度为 1D 和 2D。绝热效率用 PSP 测量，传热增强用瞬态方法使用 IR 相机获得。获得了详细的分布。吹塑比从 0.25 到 4.0 不等。密度比在 PSP 测量中为 1.0 或 1.5，仅在传热测量中为 1.0。对于后喷的简单圆柱孔，结果证实了它在高吹比下的优势，也表明其在展向方向上的绝热效果高度均匀。同时，随着 VR 的变化，后喷配置具有更稳定的冷却性能。进一步指出，简单的反向注入情况下的流场由孔出口下游的再循环区域控制。狭窄的沟槽随着前向注入大大提高了效率，而对简单的后向注入的增强却非常有限。而且，窄沟槽的性能远好于宽沟槽。结果表明，该机制的关键取决于射流与下游沟槽壁的相互作用。