• Title/Summary/Keyword: 수직분사

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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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Stochastic Model Comparison for the Breakup and Atomization of a Liquid Jet using LES (LES 해석에서 액체제트의 분열에 대한 확률론적 분열 모델링 비교)

  • Yoo, YoungLin;Sung, Hong-Gye
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.45 no.6
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    • pp.447-454
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    • 2017
  • A three-dimensional two-phase large eddy simulation(LES) has been conducted to investigate the breakup and atomization of liquid jets such as a diesel jet in parallel flow and water jet in cross flow. Gas-liquid two-phase flow was solved by a combined model of Eulerian for gas flow and Lagrangian for a liquid jet. Two stochastic breakup models were implemented to simulate the liquid column and droplet breakup process. The penetration depth and SMD(Sauter Mean Diameter) were analyzed, which was comparable with the experimental data.

The Spray Characteristics of Jet in Crossflow with the Injector Shapes (노즐 형상에 따른 Jet in Crossflow의 분무 특성)

  • Yoon, Hyun-Jin;Lim, Young-Heon;Hong, Jung-Goo;Lee, Choong-Won
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.438-444
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    • 2010
  • The spray characteristics of jet in crossflow (JICF) to improve the atomization and mixing characteristics of liquid Jet, while minimizing the impact on crossflow, were studied experimentally. By varying the temperature, velocity, pressure of crossflow and the speed, pressure of liquid Jet, the spray boundary (outer boundary, inner boundary) with the change of crossflow and liquid jet momentum ratio (q) were measured and led the experimental formula, compared with the results of previous work. Specifically, when the jet penetration with the shape of injector were measured, in the case of dual orifice Injector, under the influence of front orifice, the jet penetration of back orifice was improved approximately 18% ($L_h$ = 4 mm), compared with single orifice injector.

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Experimental Study on the Heat Transfer Characteristics on a Film-Cooled Flat Plate - Effect of Injection Angle and Blowing Rate - (막냉각되는 평판에서의 열전달특성에 관한 실험적 연구)

  • 이상우;신세현;이택시;이준식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.6
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    • pp.1415-1427
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    • 1988
  • The effect of injection angle and blowing rate on a film-cooled flat plate has been investigated experimentally. Three cases of 90.deg. injection, 35.deg. streamwise injection and 35.deg. spanwise injection are employed. The naphthalene sublimation technique in used to obtain local mass transfer coefficients. Thus heat transfer coefficients are evaluated using heat-mass transfer analogy. Schlieren photographs are taken to visualize the trajectory of injection fluid by introducing carbon dioxide gas through injection tubes. The experiments indicate that due to the injection the heat transfer coefficients increase significantly in the neighborhood of the infection holes, so the design of film cooled component must be based on the heat transfer coefficient with injection as well as film cooling effectiveness.

Unsteady Three-Dimensional Analysis of Transverse Fuel Injection into a Supersonic Crossflow using Detached Eddy Simulation Part II : Reacting Flowfield (DES를 이용한 초음속 유동내 수직 연료분사 유동의 비정상 3차원 해석 Part II : 반응 유동장)

  • Won, Su-Hee;Jeung, In-Seuck;Choi, Jeong-Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.9
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    • pp.879-888
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    • 2009
  • Unsteady three-dimensional reacting flowfield generated by transverse hydrogen injection into a supersonic mainstream is numerically investigated using DES and finite-rate chemistry model. Comparisons are made with experimental results to investigate the turbulent reacting flow physics. The numerical OH distribution describes well the experimental OH-PLIF result, while the numerical ignition delay time shows some disparity due to the restricted available experimental data. The intermittency phenomena are identified by the comparative analysis between RANS and DES. Those effects are also quantified by the temperature distributions along streamlines and superimposed OH mass fraction along with time.

Unsteady Three-Dimensional Analysis of Transverse Fuel Injection into a Supersonic Crossflow using Detached Eddy Simulation Part I : Non-Reacting Flowfield (DES를 이용한 초음속 유동내 수직 연료분사 유동의 비정상 3차원 해석 Part I : 비반응 유동장)

  • Won, Su-Hee;Jeung, In-Seuck;Choi, Jeong-Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.9
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    • pp.863-878
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    • 2009
  • Unsteady three-dimensional flowfield generated by transverse fuel injection into a supersonic mainstream is simulated with a DES turbulence model. Comparisons are made with experimental results in terms of the temporal eddy position and eddy formation frequency. The vorticity field around the jet exit is also analyzed to understand the formation mechanism of the large eddy structures. Results indicate that the DES model correctly predicts the convection characteristics of the large scale eddies. However, it is also observed that the numerical results slightly over-predict the eddy formation frequency. The large eddy structures are generated as the counter-rotating vortices are detached alternately in the upstream recirculation region.

Experimental Study on Fuel/Air Mixing using the Cavity in the Supersonic Flow (초음속 유동장 내의 공동을 이용한 연료/공기 혼합에 관한 실험적 연구)

  • Kim Chae-Hyoung;Jeong Eun-Ju;Jeung In-Seuck
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2005.11a
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    • pp.64-71
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    • 2005
  • To achieve efficient supersonic combustion within a manageable length, a successful fuel injection scheme must provide rapid mixing between fuel and airstream. In former days, various injection concepts have been investigated. Cavity flow is the open type, that is, length-to-depth ratio L/D=4.8, aft ramp angle is $22.5^{\circ}$. An experimental study on a transverse cross jet injection into a Mach 1.92 supersonic main stream which flows over a cavity was carried out to investigate the effect of the momentum flux ratio(J), the jet interaction characteristics, and the pressure distribution in the combustor and using the primary diagnostics : schlieren visualization and wall static pressure measurements. Fuel penetration height and jet interaction characteristics depend strongly on the momentum flux ratio.

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Forced Ignition Characteristics with a Plasma Jet Torch in Supersonic Flow (초음속 유동장 내 플라즈마 토치를 사용한 강제 점화 특성)

  • Kim, Chae-Hyoung;Jeung, In-Secuk;Choi, Byoung-Il;Kouchi, Toshinori;Masuya, Goro
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.04a
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    • pp.363-366
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    • 2011
  • Mixing and combustion experiments with a vent slot mixer were performed in Mach 2 supersonic wind tunnel. Helium and hydrogen gases each were used for the mixing and the combustion experiment with a plasma jet (PJ) torch. The vent slot mixer holds plenty of fuel in the downstream mixing region, even though the fuel is transversely injected. In case of the combustion, the injected fuel is ignited by the PJ torch, and then unburned mixture is burned by shock-induced combustion downstream. Thermal choking in the combustor leads to shock trains in the isolator, causing the unstable combustion.

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Structural Change of Supersonic Jet Due to Liquid Injection in Supersonic Backward Facing Step Flow (초음속 후향 계단 유동에서 액체 분사로 인한 초음속 제트의 구조 변화)

  • Ahn, Sang-Hoon;Han, Doo-Hee;Choi, Han-Young;Seo, Seong-Hyeon;Sung, Hong-Gye
    • Journal of Aerospace System Engineering
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    • v.13 no.6
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    • pp.9-16
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    • 2019
  • The experiment on the liquid jet in crossflow in supersonic BFS (backward-facing step) flow was conducted to investigate the mixing characteristics. The working fluids are nitrogen and water. The shadow graph technique was used to visualize the flow field. Images captured by the high-speed camera were applied to analyze the flow phenomena. The liquid jet was injected at the re-circulation zone created by the supersonic jet flow. Experimental conditions are defined based on the pressure of the nitrogen gas chamber and pressurized liquid tank. In respective cases, the penetration depth of liquid jet and location of the Mach disc were observed to be proportional to the momentum ratio of gas and liquid jets.

Mixing Characteristics in Supersonic Combustor with a Cavity (Cavity를 이용한 초음속 연소기 내의 혼합특성)

  • Oh Juyoung;Bae Young-Woo;Kim Ki-Su;Jeon Young-Jin;Lee Jae-Woo;Byun Yung-Hwan
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • v.y2005m4
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    • pp.359-363
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    • 2005
  • In SCRamjet engine, combustion occurs in supersonic flow with airbreathing. SCRamjet is characterized by very short combustion time in combustor, so it is very important to be mixing the air and fuel in short duration. Several methods are suggested for mixing enhancement. Among these, cavity is selected to study for enhancement of mixing. The numerical simulation is performed in the case of freestream Mach number of 2.5 and cavity located in front of fuel jet injection. CFD-Fastran, commercial code with three-dimensional Navier-Stokes equation with the Menter SST turbulence model were used. The results are obtained validate experiment results for same condition. Therefore, the numerical results show the mixing enhancement characteristics with a cavity.

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