The turbulent flow structure and vortex dynamics of a jet in a crossflow (JICF) problem, which is related to gas turbine blade film cooling, is investigated using the particle-image velocimetry (PIV) technique. A cooling jet emanating from a pipe interacts with a turbulent flat plate boundary layer at a Reynolds number Re_∞ = 400,000. The streamwise inclination of the jet is 30° and three velocity ratios VR = 0.1, VR = 0.28, and VR = 0.48 are considered. Jets of air and CO_2 are injected separately into a boundary layer to examine the effects of the density ratio between coolant and mainstream on the mixing behavior and consequently, the cooling efficiency. The results show that a higher velocity ratio enlarges the size of the recirculation region leading to a more pronounced entrainment of hot outer fluid into the wake of the jet. Furthermore, the lateral spreading of the coolant is strongly increased at a higher density ratio. The results of the experimental measurements are used to validate numerical findings. A very good agreement is found for this comparison.
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