Numerical Investigation of Installation Effects in Open Jet Wind Tunnel Airfoil Experiments

The interference between the standard open jet wind tunnel setup and the aerodynamic field of an asymmetric airfoil has been investigated in the current work using Large Eddy Simulation. The parameters influencing the midspan flow field have been identified and incorporated into the simulations in order to assess their impact on the time averaged and instantaneous flow fields. The open jet configuration and flow conditions are set to match the experimental study by Winkler et al. with a chord based Reynolds number of 1.9 × 10, low Mach number and zero angle of attack relative to the axial chord. Boundary layer trips are placed at 10% chord on both surfaces of the airfoil to suppress the large laminar separation bubble that would be otherwise present. It was shown that finding a free stream angle of attack correction that reproduces the mean pressure distribution obtained in the open jet is not possible, which is in agreement with the findings of Brooks et al. However, a correction that gives a reasonable pressure distribution match was used to compare the open jet and free stream flow fields. It was found that the transport of turbulence from the free shear layer to the vicinity of the airfoil’s trailing edge and its near wake is significant. The observation was verified by comparing mean and root mean squared velocity profiles extracted from the open jet and free stream simulations near the trailing edge and in the airfoil’s wake.