A Numerical Investigation of the Dominant Characteristics of A Transonic Flow Over A Hemispherical Turret

Abstract

The transonic characteristics of a flow over a hemispherical turret with a freestream Mach number M∞ of 0.8 are numerically studied. The flow field is simulated using the improved delayed detached eddy simulation (IDDES) with a modified sub-grid scale. The results using the adopted medium and fine grids, including for the mean pressure coefficients and the incoming boundary layer, match experimental data very well. It is observed that the wake fluctuates periodically as the shock moves upstream and downstream. The dominant flow characteristics are identified along with their frequencies. The first two proper orthogonal decomposition (POD) modes show a lateral shift of the wake, fluctuating at a Strouhal number (St) of 0.15–0.2. Modes 3 and 4 show a wall-normal fluctuation of the wake with St of 0.35. A dynamic mode decomposition (DMD) gives St values of the lateral shift and wall-normal fluctuation of 0.1813 and 0.3467, respectively.