• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.58-65
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• 2018

To improve the performance of high-speed vehicles, various studies have been carried out on the head of vehicles. In this study, tests are conducted on flow characteristics and drag reduction using counterflow air jets in supersonic flow. The flow is visualized by the Schlieren method using a high-speed camera, and the drag is measured using a torque sensor according to the injection pressure conditions. The results of the measurements indicate that the flow changes from unsteady state to steady state for injection pressure ratios between 1.58 and 1.70, and drag reduction is observed as the pressure of the counterflow air jets increases.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.6
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• pp.57-63
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• 2017

In this study, the fundamental test for drag reduction is carried out by using a plasma generator. Fundamental test setup is constructed of visualization and drag measurement system. The schlieren technique is used to visualize the plasma counterflow in supersonic flow. The penetration of the plasma jet and the change of the flow structure are observed through visualization results. Load cell is used to confirm possibility of drag reduction. Results show that drag was reduced by 6.2% using plasma jet in supersonic flow.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.905-911
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• 2017

Effects of injector position and momentum flux ratio on a vertical jet in a cross flow field were studied qualitatively and shown by using air and water. The experiment was carried out by fixing the momentum flux ratio and varying the position of the injector hole. Conversely, the injector hole position was fixed and the momentum flux ratio was varied. Image visualization was performed by a Shadowgraph technique using a high speed camera. The visualized images were compared for finding differences in spraying through Density Gradient Magnitude Image. It is observed that as the x/d of the apparatus increased the jet break up height decreases and the spray angle also decreases. When x/d is 0, the spray reaches the floor and ceiling at any momentum flux ratio.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.88-96
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• 2018

Effects of injector position and momentum flux ratio on a vertical jet in a cross-flow field are qualitatively studied and displayed using air and water. The position of the injector hole and the momentum flux ratio is changed and image visualization is performed using a shadowgraph technique and a high-speed camera. The visualized images are compared to find differences in spraying using density gradient magnitude image. It is observed that, as the x/d of the apparatus increases, the jet break-up height decreases. When x/d is 0, the spray reaches the bottom and ceiling at any momentum flux ratio.