Decoupled assessment of the effect of upstream jets on downstream film cooling on a vane

Film cooling is one of the most effective cooling methods for turbine vanes. Multi-row holes are usually used to inject coolant to reduce the vane surface temperature. The upstream film jet has both flow interference and cooling superposition on the downstream film jet. How to decouple and quantify these two effects is particularly important for conducting refined thermal analysis of turbine vanes. In this study, a double row of holes was set up on the pressure surface. By changing the cooling medium, the flow interference effect of the upstream jet on the downstream jet was separated. Then, the heat and mass transfer analogy is used to convert the concentration mixing process into a heat transfer process, thereby realizing the decoupling analysis of flow interference and cooling superposition. The study revealed that the injection of the upstream jet slightly improved the cooling effect behind the downstream hole. The hole spacing (p/d) and row spacing (S/d) affect the flow interference of the upstream film jet on the downstream film jet. Increasing the hole spacing reduces the flow interference of adjacent jets, and the influence of the upstream jet begins to appear. Increasing the row spacing causes the upstream film jet to dissipate more severely before reaching the downstream film hole, and its influence on the downstream film jet gradually decreases. When using laidback fan-shaped holes, the flow interference of the upstream jet on the downstream jet reduces the cooling effectiveness when the cooling superposition is still the main reason for the cooling gain.