A Numerical and Experimental Evaluation of the Turbulent Heat Flux in a Heated Jet in Crossflow

The injection of fully-developed turbulent heated air from a tube into a cooler turbulent duct flow is examined, as an analogy to film cooled turbine blades. Scale Resolving Simulations (SRS) are used to examine the flow numerically. A Detached Eddy Simulation (DES) methodology is examined but found to be ineffective at correctly capturing the physics of the flow. A Large Eddy Simulation (LES) numerical model is developed and applied in which tube and duct turbulence inflow effects are emulated using a divergence-free synthetic eddy method (SEM). The LES sensitivity to the synthetic inflow turbulence is examined with a series of simulations with the SEM inflow toggled on and off. The effects of turbulence in the coolant tube are found to the most critical for accurate prediction. For direct comparison, a hot-wire experiment is conducted within the ERB test cell SW-6 at NASA Glenn Research Center. Excellent agreement is obtained for these numerical and experimental results related to velocity, temperature, and heat flux, for a blowing ratio of 1.2, and involving a 36 K temperature difference. The relative effect on the solutions of tube and duct inflow turbulence is systematically evaluated. The impact of inherent low-pass filtering of temperature measurements and probe wire offset on the experimental results are addressed. The validity of the gradient diffusion hypothesis, fundamental to Reynolds-Averaged Navier-Stokes (RANS) models, is evaluated