Comparison of Showerhead Film Cooling and Double Wall Cooling in a Guide Vane Leading Edge with Hot Streak

Abstract

Under the realistic running conditions of gas turbines, the temperature at mainstream inlet is always non-uniform due to the effects of combustion process, and different types of hot streak (HS) could be found at the inlet. The existence of HS may result in some potential negative impacts on the cooling performances of vane leading edge (LE). Nowadays, the two configurations, i.e., traditional showerhead film cooling (SFC) and novel double wall cooling (DWC), have been widely used in LE designs of turbine vanes, but until now there is no comprehensive study to evaluate the two models considering HS effects. In this work, using the two cooling structures, four different temperature profiles are considered at the mainstream inlet of the cascade. The results reveal that: in both models, HS could cause a local high-temperature region on LE, and the thermal characteristics of this area are dependent on HS pattern. Compared to SFC, DWC shows a better cooling ability and a lower thermal stress on the vane surface. The cooling characteristics in DWC model are less sensitive to the HS pattern. However, the problem of the extremely high thermal stress within the pin-fins of DWC should be carefully considered.