Study of velocity fluctuations in the plenum of a 3/4 open jet automotive wind tunnel

The present study is an assessment of velocity fluctuations in a 3/4 openjet type wind tunnel using both CFD and test methods. A virtual wind tunnel was created out of the plenum of the 1∶15 scaled wind tunnel. Simulations were first carried out for the flow inside the plenum of the scaled wind tunnel using the URANS. The inlet boundary condition was defined as the combination of a constant mean velocity and an oscillating component. Both the oscillating frequencies and the mean velocities were varied in the simulations. Test for the same scale wind tunnel was carried out. Both the test and the simulation lead to the same results, showing that the unsteady flow grows in the plenum in the flow direction and the leading oscillation has a frequency of 20Hz.