Experimentally informed optimization of turbulent diffusivity for a discrete hole film cooling geometry

• A combined experimental and numerical technique is used.
• We introduce a process that uses MRI data to calculate turbulent diffusivity.
• An anisotropic turbulent diffusivity for a film cooling geometry is calculated.
• A linearly-varying turbulent diffusivity for a film cooling geometry is calculated.

A process has been developed by which mean velocity and concentration measurements can be used to determine optimal turbulent diffusivity values for an angled jet in cross-flow configuration. This configuration has applications in film cooling for gas turbine blades. The measurements, obtained by magnetic resonance imaging techniques, provide 3D time-averaged velocity and concentration fields. The mean velocity field is fed into a Reynolds-Averaged Advection Diffusion solver, which uses a turbulent diffusivity model to solve for the mean coolant concentration distribution. This distribution can be compared to the experimentally-obtained concentration field by means of an error metric that quantifies the difference between the computational and experimental concentration fields. By minimizing this error, an optimal value of the turbulent diffusivity can be determined. This optimized distribution is then compared to a RANS simulation to evaluate the relative contribution to error of the turbulent momentum flux model versus the turbulent scalar flux model.