Effects of the Plasma Actuation on the Asymmetric Vortex around an Ogive Body at High Incidence

Abstract

Time accurate numerical simulations are performed for the flow field around a vonKárman ogive with fineness ratio of 3.5 under the plasma actuation near the nose tip in a freestream of M=0.1 and Re D =220,000 to evaluate the effects of the actuation. The moving wall boundary condition is employed to model the plasma actuation. The velocity of the moving wall is correlated by the momentum produced by the plasma actuator on a flat plate using PIV measurements. The flow separation is promoted so that the pressure increases and the vortex is lifted up on the actuation side. Steady side forces with increasing magnitude are observed with increasing moving wall velocity. Increasing the moving wall velocity increases the rate of spatial evolution of the vortex asymmetry in the axial direction. The behavior of the side force observed in the simulation in terms of direction and magnitude in response to the actuation agrees with the observations in the wind tunnel test conducted by the authors under the same model geometry and freestream condition. NomenclatureC p = pressure coefficient Cz = force coefficient in the yaw direction (positive toward the port from the starboard) D = Base diameter of the ogive model M = Mach number Re D = Reynold's number based on D U ∞ = Magnitude of the freestream velocity U w = Magnitude of the moving wall velocity u = Velocity component in the horizontal direction v = Velocity component in the vertical direction x = Longitudinal axis of the ogive model (positive toward the base from the nose)  = Angle of attack

Closed Loop Flow Control of a Tangent Ogive at a High Angle of Attack

“…3(b)) to mimic the plasma actuators used in the accompanying experiment. 21 Finally, a small pin shaped disturbance was added at 90 • to the starboard side of the model. The pin had a diameter of 0.01 cm and was 0.0045 cm tall.…”

Flow Control

“…While these velocities are much greater then those generated by the plasma actuators in the experiments, the resultant wall jets downstream of the actuator are similar. Lee et al [2012] Figure 71 shows the resultant side force on the model for a moving wall velocity of 12 m/s, where the actuation is switched from the starboard to the port side every 300 ms. As shown, there is a delay (≈ 100 ms) between the time actuation is turned on and the time when the side force fully switches sides and locks into its new value. From the simulations, it takes approximately 50 ms (five convective time scalesLanser and Meyn [1994]) before the side force begins to respond to the forcing input.…”