Effect of Slot Area Ratio and Slot Angle on Swirl Cooling in a Gas Turbine Blade Leading Edge

This paper numerically simulated a swirl cooling system to study the influences of the slot area ratio and slot angle on the flow field and heat transfer performance. Numerical simulations were performed for different coolant inlet to outlet slot area ratios (1, 2, 3, and 4) and slot angles (60 degrees, 75 degrees, 90 degrees, and 105 degrees) at different Reynolds numbers. Results indicate that large-scale vortices and small circular or oval vortices are generated in the cooling channel at different slot area ratios and slot angles. At identical Reynolds numbers, the cooling system achieved 30% and 23% increases in global Nusselt number and thermal performance factor, respectively, when the slot area ratio increased from 1 to 4. Although the system obtained only a 7.5% increase in global Nusselt number, it achieved a 29.8% increase in thermal performance factor when the slot angle increased from 60 degrees to 105 degrees at fixed Reynolds number. The applied cooling system is recommended for the internal swirl cooling of a gas turbine blade leading edge at optimum values of design parameters at a slot area ratio of 4 and slot angle 105 degrees at high Reynolds number.