Experimental and Numerical Investigation of Sweeping Jet Film Cooling
A companion experimental and numerical study was conducted of the performance of a row of 5 sweeping jet (SJ) film cooling holes consisting of conventional curved fluidic oscillators with an aspect ratio (AR) of unity and a hole spacing of P/D = 8.5. Adiabatic film effectiveness (η), thermal field (θ), convective heat transfer coefficient (h) and discharge coefficient (CD) were measured at two different freestream turbulence levels (Tu = 0.4% and 10.1%) and four blowing ratios (M = 0.98, 1.97, 2.94 and 3.96) at a density ratio (DR) of 1.04 and hole Reynolds number of ReD = 2800. Adiabatic film effectiveness and thermal field data were also acquired for a baseline 777-shaped hole. The sweeping jet film cooling hole showed significant improvement in cooling effectiveness in the lateral direction due to the sweeping action of the fluidic oscillator. An unsteady RANS simulation was performed to evaluate the flow field at the exit of the hole. Time resolved flow fields revealed two alternating streamwise vortices at all blowing ratios. The sense of rotation of these alternating vortices is opposite to the traditional counter rotating vortex pair (CRVP) found in a ‘jet in crossflow’ and serves to spread the film coolant laterally.