Leading Edge Cooling of a Gas Turbine Blade With Double Swirl Chambers
The gas turbine blade leading edge area has locally extremely high thermal loads, which restrict the further increase of turbine inlet temperature or the decrease of the amount of coolant mass flow to improve the thermal efficiency. Jet impingement heat transfer is the state of the art cooling configuration, which has long been used in this area. In the present study, a modified double swirl chambers cooling configuration has been developed for the gas turbine blade leading edge. The double swirl chambers cooling (DSC) technology is introduced by the authors and comprises a significant enhancement of heat transfer due to the generation of two anti-rotating swirls. In DSC cooling the reattachment of the swirl flows with the maximum velocity at the middle of the chamber leads to a linear impingement effect, which is most suitable for the leading edge cooling for a gas turbine blade. In addition, because of the two swirls both suction side and pressure side of the blade near the leading edge can be very well cooled. In this work, a comparison among three different internal cooling configurations for the leading edge (impingement cooling, swirl chamber and double swirl chambers) has been investigated numerically. With the same inlet slots and the same Reynolds number based on hydraulic diameter of channel the DSC cooling shows overall higher Nusselt number ratio than that in the other two cooling configurations. Downstream of the impingement point, due to the linear impingement effect, the DSC cooling has twice the heat flux in the leading edge area than the standard impingement cooling channel.