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The purpose of the research is to develop the method of designing and manufacturing a sensitivity-adjustable three component force balance utilized in a wind tunnel experiment. This paper describes the characteristics of the force balance and its application to wind tunnel testing. In this study, an oval-shape force balance is newly introduced and the characteristics are investigated by FEM analysis and force balance calibration. Also, the validity of the force balance is investigated in a wind tunnel experiment. As a result, the sensitivity of the oval-shape force balance can be adjusted by changing the aspect ratio and aerodynamic forces can be measured in a wind tunnel experiment using it. In conclusion, we can develop the sensitivity-adjustable force balance by applying oval shape and the force balance can be used in a wind tunnel experiment. It is recommended that the strain gauge position and its paste procedure be still improved.

A delta wing with a sawtooth leading edge has an ability to improve its aerodynamic performance, which was suggested and confirmed by the authors' previous study [1]. It should not be practical, economical and easily controllable, because the sawtooth configuration part extends from the apex of the delta wing to the trailing edge. In this research a few petit delta parts beside the whole sawtooth leading edge was suggested on the basis of computational fluid dynamics (CFD) results for its optimization by changing their location on the leading edge, the number of petit deltas, and the configuration of the petit part. The aerodynamic characteristics of the suggested wing were investigated by experimental as well as numerical studies with the comparison to both the base delta wing without a sawtooth leading edge and the whole sawtooth delta wing. It was found that a series of three petit deltas with the modified rear configuration, which are located at the middle of the leading edge, gives the best performances at the attack angle for its taking off and landing. The reason for the best lift and such the complicated flow field as the primary leading edge separation vortex interacting with the flow from the petit deltas was examined in detail.

The flow control performance of the pulse-actuated plasma actuator and their mechanism was investigated. To clarify the flow mechanism of the separation control on a circular cylinder when pulsed plasma actuator is applied, the characteristics of the induced jet and their influence on the separated flow were separately examined. The characteristics of the induced jet from the pulsed plasma actuator were examined from the results of jet thrust measurement and high-speed Schlieren flow visualization. The effect of the frequency of pulsed plasma actuator on the flow separation on a circular cylinder model is examined in the viewpoint if aerodynamic force and the flow field measured with time-resolved PIV at the low speed wind tunnel test. For the induced jet analysis, the strength of the induced jet is found to be widely varied with the modulation frequency. When the modulation frequency is high, over 250Hz, the thrust of the induced jet increases with the modulation frequency increased. For the separation control test, the drag is significantly dropped with increasing the modulation frequency. From these results, it turns out that the enhancement of the induced jet generated from plasma actuator in high modulation frequency regime is the main cause of the enhancement of drag reduction performance.