• 제목/요약/키워드: Jet flow velocity

검색결과 489건 처리시간 0.026초

속도차가 존재하는 두 분류의 2상유동에 관한 연구 (Study on Two Phase Flow of Two Jets Existing Velocity Difference)

  • 양희천
    • Journal of Advanced Marine Engineering and Technology
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    • 제22권4호
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    • pp.515-521
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    • 1998
  • In this study the mixing process of two-phase flow which makes two jets existing vlocity difference are analyzed. The primary jet is jetted on the condition of the state mixed pulverized solid pariticle with air and the velocity in the secondary jet is changed into three kinds velocities(0.60, 75m/s) The velocity vector field concentration field and turbulent properties of solid particles are measured by using 3-Dimensional Particles Dynamics Analyzer. As the velocity of secondary jet increases the solid particle recirculation zone becomes larger. Also solid particle concentration gets dense due to velocity decrement of particles.

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관통 손상 구멍으로부터의 제트-교차 흐름의 유동장 구조 (The Flow Field Structure of Jet-in-Cross Flow through the Perforated Damage Hole)

  • 이기영
    • 한국군사과학기술학회지
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    • 제17권4호
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    • pp.551-559
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    • 2014
  • The influence of the battle damage hole on the velocity and vorticity flow field have been studied by using particle image velocimetry. Time averaged velocity and vorticity vector fields in the vicinity of jet are presented. The perforated damage hole on a wing created from a hit by anti-air artillery was modeled as a 10% chord size hole which positioned at quarter chord. At low angles of attack, the vorticity in the forward side of the jet is cancelled due to mixing with the wing surface boundary layer. Stretching of vorticity in the backside of the jet generates a semi-cylindrical vortical layer that enclosing a domain with slow moving reverse flow. Conversely, at higher the angles of attack, the jet vorticity advected away from the wing surface and remains mostly confined to the jet. The mean flow behind the jet has a wake-like structure.

동축제트의 와류주파수 및 혼합특성에 대한 수치해석 (NUMERICAL STUDY ON THE CHARACTERISTICS OF VORTEX FREQUENCY AND LAMINAR MIXING OF A PASSIVE SCALAR IN COAXIAL JET FLOWS)

  • 김원현;박태선
    • 한국전산유체공학회지
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    • 제14권3호
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    • pp.49-55
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    • 2009
  • This study focuses on the near-field vortical structure and dynamics of coaxial jets. The characteristics of laminar flow and mixing in coaxial jets are investigated using a unsteady flow simulation. In order to analyze the geometric effects on the vortical structure, several cases of different configurations are selected for various values of the velocity ratio of inner jet to outer jet. From the result, it is confirmed that the flow mixing is promoted by the development of vortical structure and the interaction between inner jet and outer jet. This feature is strongly related to the vortex frequency in the shear-layers. The vortex frequency depends on the velocity ratio and the lip thickness of inner nozzle, but the outer pipe length has no effect on the frequency variation.

중력방향과 대향류인 저속 원형노즐 제트충돌에 의한 원형평판에서의 열전달 현상 (The Study of Heat Transfer on a Heated Circular Surface by an Impinging, Circular Water Jet with the Low Velocity Against the Direction of Gravity)

  • 김기태;엄용균
    • 대한기계학회논문집B
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    • 제33권12호
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    • pp.983-991
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    • 2009
  • The heat transfer phenomenon was investigated in this study when a circular water jet with low velocity flows to the downward facing heated circular plate and against the direction of gravity. Data are presented for jet flow rate between 0.23 and 2.3 l/min, jet fluid temperature of 24$^{\circ}C$, heat fluxes between 345 and 687 W/m$^2$, H/D=1, 2 and 3 with a single round jet diameter 2mm. The effects of heat flux, jet velocity and H/D on the local heat transfer are investigated in for the various regions of jet impingement. The local heat transfer distributions are analyzed based on the visualization of jet flow field. Data from experimental results are correlated by expressions of the form Nu=0.01$Re^{0.58}{\cdot}Pr^{0.4}$.

분사각 변화에 따른 횡단류에 분사되는 액체제트의 분무특성에 대한 수치적 연구 (Numerical Study for Spray Characteristics of Liquid Jet in Cross Flow with Variation of Injection Angle)

  • 이관형;고정빈;구자예
    • 대한기계학회논문집B
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    • 제30권2호
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    • pp.161-169
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    • 2006
  • The spray characteristics of liquid jet in cross flow with variation of injection angle are numerically studied. Numerical analysis was carried out using KIVA code, which was modified to be suitable for simulating liquid jet ejected into cross flow. Wave model and Kelvin-Helmholtz(KH)/Rayleigh-Taylor(RT) hybrid model were used for the purpose of analyzing liquid column, ligament, and the breakup of droplet. Numerical results were compared with experimental data in order to verify the reliability of the physical model. Liquid jet penetration length, volume flux, droplet velocity profile and SMD were obtained. Penetration length increases as flow velocity decreases and injection velocity increases. From the bottom wall, the SMD increases as vertical distance increases. Also the SMD decreases as injection angle increases.

낮은 속도비에서의 직렬 이중 제트-교차흐름의 유동 구조 (The Flow Field Structures of In-lined Double Jet-in-Cross Flow at Low Velocity Ratio)

  • 이기영
    • 한국군사과학기술학회지
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    • 제18권4호
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    • pp.415-422
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    • 2015
  • The flow field structures of dual jet-in-cross-flow were examined experimentally for in-lined perforated damage holes configuration using particle image velocimetry. Ensemble averaged in-plane velocity and vorticity data in the jet were determined to study the mean jet structure. Jets are formed by pressure differences between upper and lower airfoil surface. The flow structure of vicinity of the thru holes consist of a vortical structure that wrap around the jets like a horseshoe and develop further downstream through a pair of stream-wise vortices. The shape, size and location of the horseshoe vortex were found to be dependent on the angle of attack. In spite of the existence of battle damage holes, the effect on the control force was insignificant when the damage size was not large enough.

Jet가 분출되는 채널내 정사각단면 실린더 주위유동 및 혼합현상 (Confined laminar vortex shedding and scalar mixing around a square cylinder with a jet)

  • 엄준석;김도형;양경수
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 춘계학술대회논문집B
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    • pp.759-764
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    • 2000
  • In this study, the confined laminar flow around a square cylinder, which ejects a either on the front face or on the rear face, is numerically simulated. In each case, three ratios of jet velocity to the fixed upstream velocity are considered. In all cases of the rear fuel jet, the high mass-fraction region is formed along the streamlines from the jet exit. In case of front jet, drag is significantly decreased when the jet velocity ratio is greater than 1. The results obtained exhibit flow and scalar-mixing characteristics encountered in a planar combustor

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천해역에 방류되는 원형 다공바닥젵의 유속구조 (Velocity Structure of Wall Jet Originating from Circular Orifices in Shallow Water)

  • 김대근;서일원
    • 한국환경과학회지
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    • 제11권10호
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    • pp.1039-1044
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    • 2002
  • In this study, breakwater model which has several outlet pipes to discharge water is settled in the experimental open channel and mean velocity distributions of multi wall jet are measured. The length of zone of flow establishment of wall jet is shorter than that of free jet and decay rate of jet centerline longitudinal velocity along x is linear in $0.3{leq}x/I_p{leq}17$. The rate of vertical width and lateral width spreading of multi wall jet is respectively 0.0753, 0.157.

동축이중원관 분류에 있어서의 유동 특성에 관한 연구 (A Study on the Flow Characteristics in Double Coaxial Pipe Jets)

  • 신창환;김경훈
    • 한국분무공학회지
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    • 제1권4호
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    • pp.46-53
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    • 1996
  • The present study is aiming at improving the performance of main nozzle of an air jet loom with a modified reed and auxiliary nozzles. The double coaxial pipe jets consisting of a central air jet and an annular air jet have been experimentally investigated. The duter jet has a potential core and a constant velocity. The inner jet through an inner long pipe is induced by the subatmospheric pressure near the inner nozzle edge, and the jet velocity of an inner pipe is always lower than that of a outer pipe. The static pressures of the main nozzle over a wide range of the nozzle tank pressure were measured, and the nozzle velocity and Mach numbers were analytically calculated. Experiment81 results indicate that the critical condition of Mach number of unity to occur at the two positions in a main nozzle; one of them is the needle tip and the other is the acceleration tube exit An increase in the tank pressure causes the critical throat condition to occur at the two positions above. The velocity of acceleration-tube exit is maximum at the critical length L* and flow patter in acceleration-tube over critical lengh remains unstable.

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가진된 부착화염에서 거대와동의 거동 (Behavior of the Coherent Structure on the Attached Forced Flame)

  • 김대원;이기만
    • Journal of Advanced Marine Engineering and Technology
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    • 제33권2호
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    • pp.259-266
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    • 2009
  • An experimental study was conducted to investigate the effects of forcing amplitude on the flow structure near the nozzle exit of forced jet diffusion flames. The jet was excited up to the blowout occurrence by a considerable large amplitude with a periodic velocity fluctuation at the tube resonating frequency. In the attached flame regime, we disclosed the very interesting result newly that adding of a moderate forcing amplitude caused the jet flame to become longer in spite of being forced. Particular attention is focused on the turnabout mechanism of vortex roll-up around the elongated flame, which has not been reported previously, and on the inner coherent structure of the forced jet in the attached flame regime. From the velocity and flow visualization results, it was ascertained that the surrounding air due to the occurrence of negative velocity parts was suck into the fuel nozzle. To aid in understanding the rotating phenomenon of coherent structure, we present a schematic diagram of the turnabout mechanism of vortex roll-up. The mechanism of vortex turnabout phenomenon can be easily understood by considering the positive and negative velocity amplitudes about the instantaneous velocity of the forcing flow, as shown in this diagram.