Numerical Investigation of Flow Control for a Flat-Window Cylindrical Turret

This work presents multiple high-fidelity large-eddy simulations of flow over a cylindrical turret with a flat window oriented at two angles, 90 and 100 deg. For the 100 deg case, additional computations were performed to investigate the effectiveness of multiple types of flow control including rows of short pins, tall pins, and steady blowing wall jets inserted upstream of the turret as well as a steady suction slot at the leading edge of the flat window. The large-eddy simulation computations were obtained using a well-validated high-order Navier–Stokes flow solver employing a sixth-order compact spatial discretization in conjunction with an eighth-order low-pass spatial filter. Overall, large-eddy simulation solutions compared favorably to experimental time mean and fluctuating velocity profiles as well as the general flow structure at both angles. Additionally, valuable insight was obtained on how rows of pins, blowing jets, and steady slot suction control flow separation. Slot suction at the upwind aperture lip was determined to be more effective than rows of pins and blowing jets in controlling flow separation, which is critical in reducing aero-optical aberrations. Steady slot suction was capable of eliminating massive separation at a larger look angle of 120 deg.