Separation control mechanism of airfoil using synthetic jet

Abstract

Numerical simulation of separation control using a synthetic jet was performed on NACA23012 airfoil. The computed results showed that stall characteristics and control surface performance could be improved substantially by resizing the separation vortices. It was observed that actual flow control mechanism was fundamentally different depending on the range of synthetic jet frequency. For low frequency range, small vortices due to synthetic jet penetrated to the large leading edge separation vortex flow, and as a result, the size of the leading edge separation vortex remarkably decreased. For high frequency range, however, the small vortex did not grow enough to penetrate into the large separation vortex, but the syntheticjet changed airfoil circulation directly. The synthetic jet conditions for effective lift increase are as follows: the non-dimensional frequency of the synthetic jet is I; the location of the synthetic jet slot is the same as the separation point; and the jet velocity is large enough to perturb the separated flow. By exploiting these conditions, it was observed that the combination of the synthetic jet with a simple high lift device could be as good as a conventional fowler flap system.

Numerical Study on the Mass Transfer in a Two-Dimensional Channel with the Transversely Oscillating Wall

“…In connection with this problem, we take up the synthetic jet (9), (10) . The restraint of the flow separation has an important meaning in various fields such as the design of the aircraft.…”

“…So, the theoretical and experimental studies on the devices to restrain the flow separation have been carried out for a long time. Among these devices, the synthetic jet has been shown to be a useful tool for the separation control (9), (10) . The synthetic jet consists of the orifice driven by the acoustic source in a cavity.…”

“…So, we can easily expect that this transport can re-energize the boundary layer under a certain condition when the boundary layer begins to weaken and approach separation. After all, the boundary layer energization will lead to the restraint of the flow separation (9), (10) . From these considerations, we can understand the physical mechanism of the synthetic jet easily.…”

Active Flow Control by Using Plasma Actuators

“…These devices can be used to mimic classical synthetic jets and are usually called plasma synthetic jet actuators (PSJA). Typical geometries are annular and linear one [48,[59][60][61][62]. In both cases, tangential wall jets collide merging in a unique-induced jet able to generate perturbations far away from the actuator surface (Figures 10 and 11).…”

Wind Tunnel Experiments on a NACA0015 Airfoil Equipped with Vectorizable Dielectric Barrier Discharge Plasma Actuators

“…A plasma aerodynamic actuator, able to generate a vectorizable jet, could simulate the presence of a fluid dynamic actuator as a synthetic jet. The use of these devices in airfoils delays the stall and enhances the lift 17,18 . In last years several investigations have dealt with Plasma Synthetic Jet Actuators (PSJA) built by means of DBDs or Sliding Discharges in annular and linear configurations [19][20][21][22][23][24][25][26] .…”