Numerical investigation of flow and heat transfer on turbine guide vane leading edge slot film cooling

As the demand for enhanced turbine cooling performance grows, the optimization of traditional discrete film hole is becoming increasingly complex. Compared with discrete holes, slot cooling is considered one of the most effective forms of film cooling, which effectively improves cooling performance while retaining a relatively simple structure. In order to explore the flow and heat transfer properties of leading-edge slot film cooling in turbine vanes, this paper analyzes the AGTB guide vane profile to examine the properties of the slot structure under different slot pitch-to-width ratios and blowing ratios (M), deeply investigates the evolution and underlying mechanism of the secondary flow downstream the slot and within the vane passage, comparisons are also made with standard cylindrical hole and inclined hole. The results show that the development of the counter-rotating vortex pairs on the pressure surface lags and extends over a longer distance downstream of the slot. Reducing the slot spacing can enhance the mutual interference between the vortex pairs, significantly improving the cooling performance on the pressure surface. On the suction side, the coolant streams remain largely independent, and both increasing M and reducing slot spacing adversely affect cooling performance. Under the same M, the slot structure achieves an average cooling effectiveness 2–3 times higher than the hole structure, accompanied by a 25 % increase in total pressure loss. At the same coolant mass flow, the cooling effectiveness on the pressure surface increases by approximately 30 %, and on the suction surface, it is three times greater than that of the hole structure, while the total pressure loss remains similar.