Effects of hole-inlet velocity on the adiabatic film cooling effectiveness behind crossflow-fed shaped holes

Abstract

In this contribution, the effect of hole-inlet velocity ratio (VRin) on adiabatic film cooling effectiveness behind crossflow-fed shaped holes is quantified using fast-response pressure-sensitive paint (fast-PSP). The measurement was performed at VRin = 0.38 and VRin = 0.5. For VRin = 0.38, the coolant and channel velocities (VRc &VRch, respectively) were varied as either VRc = 0.8 &VRch=0.3 or VRc = 1.6 &VRch=0.6, while VRin = 0.5 varies as either VRc = 0.8 &VRch=0.4 or VRc = 1.2 &VRch=0.6. The spatial–temporal features of the measured effectiveness were uncovered by the mean and unsteady data. The result affirmed the performance deterioration, which was associated with the asymmetric spreading behind the holes. The channel velocity ratio contributed to the coolant biasing, while the coolant velocity ratio contributed to the coolant spreading. The effectiveness (time-average and statistical) was correlated with identical VRin regardless of VRc &VRch; revealing the similarity and distinction from a qualitative and quantitative point of view, respectively. Based on the analysis, the obtained features indicate the coolant promotion at lower flow conditions (VRc &VRch) for both VRin = 0.38 and VRin = 0.50, although it's higher unsteadiness. Based on SOM, this could enhance the coolant coverage by the fluctuations than the local overheating by the mainstream gases. This research could assist designers to understand the unsteady features, as well as promote new cooling solutions for improved gas turbine protection in the future.