Abstract
The overall cooling effectiveness(ϕ) is used to provide the actual temperature on the surface of the turbine vane, which is measured using IR thermography with high resolution and dynamic range in current study. The effects of geometrical parameters of turbine vane leading edge on ϕ _are experimentally and numerically investigated. Three specimens of turbine vanes are investigated including two wall thicknesses (2.28mm,5.7mm) and two film cooling hole diameters (0.95mm,0.66mm). In addition, the total areas of the film holes outlets for specimens are the same to ensure similar flow resistance characteristics. The experiments are modelled in a low-temperature state(Tg=583K, Tc=293K). The mainstream Reynold number (Reg) is 165,000, and four typical mass flow ratios (MFR) are designed, 0.35%, 0.52%, 0.69% and 1.02%. Results show that: the hole diameter plays a pivotal role on ϕ _distirbution. Two vanes with smaller diameter of film hole have higer overall cooling effectiveness than the model with larger diameter at all MFR conditions. The ϕ _distributions are nonhomogeneous along the streamwise and lateral direction, especially at low MFR conditions for three vanes. This is mainly caused by the uneven coolant flow distribution at low MFR. However, the ϕ _distribution will be more uniform as the MFR increases due to the denser coolant outflow at each hole row. Furthermore, the influence of wall thicknesses on ϕ _is different as MFR increases from 0.35% to 1.02%, and the ϕ _of thicker wall model has a greater increase.
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