• Title/Summary/Keyword: Jet Deflection Angle

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A Study on Operation Characteristics of Co-flow Fluidic Thrust Vector Control under Over-expanded Jet Condition (동축류 이차유동 분사를 이용한 초음속 과팽창 제트유동의 유체역학적 추력방향제어 작동특성 연구)

  • Heo, Jun-Young;Jeon, Dong-Hyun;Lee, Yeol;Sung, Hong-Gye
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.5
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    • pp.416-423
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    • 2011
  • The purpose of this research is to investigate the operation characteristics of fluidic thrust vector control using injection of the control flow parallel to the main jet direction; Co-flow injection. The technique bases on the Coanda effect of flow. Both numerical and experimental studies were conducted to investigate operation parameters; flow structure, the jet deflection angle, and shock effects near the nozzle exit. While the total pressure of main jet is the range of 300 to 790 kPa, the total pressure of control flow varies from 120 to 200 kPa. The jet deflection angle and thrust coefficient have linear relation with the pressure ratio(PR) of main jet to control flow in 0.15 < PR < 0.4 but show their limit above PR = 0.4.

Study on the Fluidic Thrust Vector Control Using Co-Flow Concept

  • Wu, Kexin;Jin, Yingzi;Kim, Heuy Dong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.675-678
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    • 2017
  • In the present, various methods have been employed to obtain the lesser thrust loss. Numerical simulations have been carried out for optimizing the thrust vector control system. Thrust vector control based on coflowing shear layer is an effective method to control the primary jet direction in the absence of moving parts. Thrust vector in symmetric nozzles is acquired by secondary flow injections that result to boundary layer separation. The pressure in secondary flow inlet was varied to check the deflection angle of jet flow.

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Experimental Study of the Effect of Side Plate on the Coanda Effect of Sonic Jet (측판이 음속 제트의 코안다 효과에 미치는 영향에 관한 실험적 연구)

  • Park, Sanghoon;Chang, Hongbeen;Lee, Yeol
    • Journal of the Korean Society of Propulsion Engineers
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    • v.20 no.2
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    • pp.24-30
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    • 2016
  • An experimental study for the characteristics of the thrust-vectoring of a sonic jet utilizing the coanda flap installed at a rectangular nozzle exit is performed. Two side plates are installed at both sides of the flap to decrease the three dimensional effects of the jet on the flap surface. Schlieren flow visualizations and quantitative measurements of the deflection angle of thrusting vector show that the side plates are able to delay the separation of the jet at the downstream of the flap surface. Substantial increase in the deflection angle of the jet as high as $72^{\circ}$ and small thrust loss as low as 7% are obtained by the present thrust-vectoring technique using the side plates.

Experimental Study Of Supersonic Coanda Jet

  • Kim, Heuydong;Chaemin Im;Sunhoon, Woo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1999.10a
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    • pp.33-33
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    • 1999
  • The Coanda effect is the tendency for a fluid jet to atach itself to an adjacent surface and follow its contour without causing an appreciable flow separation. The jet is pulled onto the surface by the low pressure region which develops as entrainment pumps fluid from the region between the jet and the surface. Then the jet is held to the wall surface by the resulting radial pressure gradient which balance the inertial resistance of the jet to turning. The jet may attach to the surface and may be deflected through more than 180 dog, when the radius of the Coanda surface is sufficiently large compared to the height of the exhaust nozzle. However, if the radius of curvature is small, the jet turns through a smaller angle, or may not attach to the surface at all. In general, the limitations in size and weight of a device will limit the radius of the deflection surface. Thus much effort has been paid to improve the jet deflection in a variety of engineering fields. The Coanda effect has long been applied to improve aerodynamic characteristics, such as the drag/lift ratio of flight body, the engine exhaust plume thrust vectoring, and the aerofoil/wing circulation control. During the energy crisis of the seventies, the Coanda jet was applied to reduce vehicle drag and led to drag reductions of as much as about 30% for a trailer configuration. Recently a variety of industrial applications are exploiting another characteristics of the Coanda jets, mainly the enhanced turbulence levels and entrainment compared with conventional jet flows. Various industrial burners and combustors are based upon this principle. If the curvature of the Coanda surface is too great or the operating pressure too high, the jet flow will break away completely from the surface. This could have catastrophic consequences for a burner or combustor. Detailed understanding of the Coanda jet flow is essential to refine the design to maximize the enhanced entrainment in these applications.

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A study on structural safety evaluation of jet vane under very high temperature and dynamic pressure (초고온 동압을 받는 제트 베인의 구조 안전성 평가에 대한 연구)

  • Park Sunghan;Lee Sangyeon;Park Jongkyoo;Kim Wonhoon;Moon Soonil
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • v.y2005m4
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    • pp.99-105
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    • 2005
  • To evaluate structural safety factor of the jet vane for the thrust deflection system under the dynamic pressure and very high temperature($2700^{\circ}C$) of the combustion gas flow, the high temperature tension tests of refractory metals and 3-D nonlinear numerical simulations are performed. Through the analysis of high temperature structural behavior for jet vane, the structural safety of jet vane is evaluated, and numerical results are compared with static pound tests of jet vanes. It has been found that most of structural and thermal loading is concentrated on the vane shaft which worked as safe under $1400^{\circ}C$. From the comparison of static ground tests and numerical results, the evaluation criterion using the vane load and shaft displacement is more useful to estimate the structural safety than using the equivalent stress.

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A Study on Structural Safety Evaluation of let Vane under very High Temperature and Dynamic Pressure (초고온 동압을 밭는 제트 베인의 구조 안전성 평가에 대한 연구)

  • Park Sunghan;Lee Sangyeon;Park Jongkyoo;Kim Wonhoon;Moon Soonil
    • Journal of the Korean Society of Propulsion Engineers
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    • v.9 no.3
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    • pp.18-24
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    • 2005
  • To evaluate structural safety factor of the jet vane for the thrust deflection system under the dynamic pressure and very high temperature(2700$^{\circ}C$ ) of the combustion gas flow, the high temperature tension tests of refractory metals and 3-D nonlinear numerical simulations are performed. Through the analysis of high temperature structure behavior for jet vane, the structure safety of jet vane is evaluated, and numerical results are compared with static ground tests of jet vanes. It has been found that most of structural and thermal loading is concentrated on the vane shaft which worked as safe under 1400$^{\circ}C$. From the comparison of static ground tests and numerical results, the evaluation criterion using the vane load and shaft displacement is more useful to estimate the structural safety than using the equivalent stress.

Performance Test of a Jet vane type Thrust Vector Control System (제트 베인형 추력편향장치의 성능시험)

  • 신완순;이정민;이택상;박종호;김윤곤;이방업
    • Journal of the Korean Society of Propulsion Engineers
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    • v.3 no.4
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    • pp.75-82
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    • 1999
  • Theoretical analysis and performance test of Jet vane type Thrust Vector Control(TVC) were conducted using supersonic cold-flow system. The use of TVC Systems an in particular jet vanes, are currently being researched for use in air launch, ship launch, underwater launch and high altitude maneuvering of tactical missiles and rockets. The necessity to generate control forces to rapidly change the course of the missile is frequently required when traditional, exterior aerodynamic surfaces are unable to produce these forces, when the flow over the control surface is insufficient. This situation can occur at launch, or high angles of attack of the control surfaces. Jet vanes peformed well at all altitudes and environmental conditions, and jet vanes are extremely effective at deflection angles up to as high as $30^{\circ}$, make them ideal for the launch and maneuver applications. In this study, performance test of supersonic cold-flow system and visualization of supersonic jet was conducted, and shape and deflection angle effect of two types of jet vanes are investigated.

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An Experimental Study on the Characteristics of Rectangular Supersonic Jet on a Flat Plate

  • Kwak, Ji-Young;Lee, Yeol
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.3
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    • pp.324-331
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    • 2016
  • The present study focuses on the characteristics of a supersonic jet flowing from a rectangular nozzle exit on a flat plate. Flow visualization techniques using schlieren and kerosene-lampblack tracing are utilized to investigate shock reflection structures and boundary-layer separations over a flat plate. Wall pressure measurements are also carried out to quantitatively analyze the flow structures. All observations are repeated for multiple jet flow boundary conditions by varying the flap length and nozzle pressure ratio. The experimental results show that the jet flow structures over the flat plate are highly three-dimensional with strong bleeding flows from the plate sides, and that they are sensitive to plate length and nozzle pressure ratio. A multi-component force measurement device is also utilized to observe the characteristics of the jet flow thrust vectoring over the plate. The maximum thrust deflection angle of the jet is about $8^{\circ}$, demonstrating the applicability of thrust vector control via a flat plate installed at the nozzle exit.

The Study on Aerodynamic Characteristics for the Design of High Efficiency Jet Vane (고 효율 제트 베인 설계를 위한 공기역학적 특성 연구)

  • 길경섭;정용갑;박종호
    • Journal of the Korean Society of Propulsion Engineers
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    • v.7 no.4
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    • pp.39-45
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    • 2003
  • Of the various means for active trajectory correction, a thrust vector control system represents the only principle independent of missile external forces so that this method is operative. The purpose of this study is to analyze the characteristic of jet vane TVC(Thrust vector control) system among mechanical jet deflection. To ensure high performance leading edge shape, aspect ratio and ablated condition is optimized. Supersonic flow system, jet vanes and nozzle with Mach number 2.88 and under expansion ratio 2 were designed to study aerodynamic characteristics of leading edge shape, aspect ratio and ablated conditions.

Thrust Vectoring Control of Supersonic Jet Using Proportional Control Valves (비례제어밸브를 이용한 초음속 제트의 추력편향 제어)

  • Lee, MyungYeon;Lee, Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.1
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    • pp.1-8
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    • 2019
  • An experimental study is performed to observe the characteristics of the thrust vectoring control (TVC) of the supersonic jet using proportional control valves. It is observed that three different TVC characteristics exist as the nozzle pressure ratio varies. Strong hysteresis phenomena are also observed during the valve control for a certain range of the nozzle pressure ratio. It is also noticed that the secondary chamber pressure is one of the influencing parameters for the TVC. Therefore, a control algorithm utilizing the secondary chamber pressure coefficient as a predictor is applied to achieve the stable TVC avoiding the hysteresis. Consequently, the stable TVC with the maximum deflection angle of about 20-degree has been realized using the proportional control valves.