Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 07, 2019 - November 08, 2019
An effective method for the prevention of separation is boundary layer mixing. In this method, the fluid particles in the freestream that have large amounts of energy are supplied to decelerated fluid particles in the boundary layer using longitudinal vortices. Passive control methods such as solid vortex generators are advantageous because of its simplicity, ruggedness, and low cost. However, these methods cannot provide a time-varying control action, and they add parasitic drag in flow situations when the separation control is not needed. On the other hand, there are active control methods that can provide a time-varying control action. A synthetic jet is one of the active control methods. Synthetic jet actuators have advantages in exterior design, safety of vehicles, drag reduction and time-varying control. In this study, the effect of synthetic jets on the drag reduction of the Ahmed body was investigated. Drag measurement was performed by changing the jet-to-freestream velocity ratio and jet positions. In this experiment, two jet positions are tested to investigate the effect of the jet position. The vortical structures around the Ahmed body were visualized by utilizing a smoke wire method. Drag reductions up to 7% were obtained by suppressing flow separation over the slanted surface, and it was found that the control effect was influenced by the jet position.
