• Title/Summary/Keyword: 역분사 제트

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Flow Characteristics and Drag Reduction at Different Pressures of Counterflow Air Jets in Supersonic Flow (초음속 환경에서 역분사 공기 제트의 압력 변화에 따른 유동 특성 및 항력 감소)

  • Choi, Jongin;Lee, Jaecheong;Kang, Seungwon;Huh, Hwanil
    • 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.

Fundamental Experiments of Drag Reduction for a High Speed Vehicle Using Plasma Counterflow Jets (플라즈마 분사장치를 활용한 초고속 비행체의 항력감소 기초 실험)

  • Kang, Seungwon;Choi, Jongin;Lee, Jaecheong;Huh, Hwanil
    • 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.

Spray Characteristics of Jet According to Position of Injector Hole in Cross Flow (횡단유동내 인젝터 홀의 위치에 따른 제트의 분무 특성)

  • Choi, Myeung Hwan;Shin, DongSoo;Radhakrishna, Kanmaniraja;Son, Min;Koo, jaye
    • 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.

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Spray Characteristics of Jet According to Position of Injector Hole in Crossflow (횡단유동내 인젝터 홀의 위치에 따른 제트의 분무 특성)

  • Choi, Myeung Hwan;Shin, Dong Soo;Radhakrishnan, Kanmaniraja;Son, Min;Koo, Jaye
    • 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.