Sensitivity of Laidback Fan-Shaped Hole Discharge Coefficient Under Internal Coolant Crossflow Conditions

An experimental study was performed on the discharge coefficients of laidback fan-shaped holes under different internal coolant crossflow orientations. The influence of the geometric and flow parameters on the discharge coefficient was investigated under flat plate conditions, where the pressure ratio ranged from 1 to 1.6. The results show that the film hole discharge coefficient is more sensitive to variations in the coolant crossflow under small pressure ratios. In comparison, the discharge coefficient is much less sensitive to the change of coolant crossflow under high pressure. Meanwhile, the length of the cylindrical section varied over the range of 1D–4D, and the length of the expansion section varied from 2D to 6D, where D represents the diameter of the film hole. The results show that the discharge coefficient is much more sensitive to the length of the cylindrical section than to the length of the expansion section. To quantify the sensitivity of the internal crossflow effects on the discharge coefficient, a low-ordered reduced model is proposed for the discharge coefficient of laidback fan-shaped holes. Both the geometric and flow parameters are considered in the model and give prediction errors within 5%.