• 제목/요약/키워드: like-doublet injector

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Like-Doublet 인젝터의 분무 질량분포 측정을 위한 PLLIF기법의 신뢰성 평가 (Assessment of PLLIF Measurement for Spray Mass Distribution of Like-Doublet Injector)

  • 정기훈;고현석;윤영빈
    • 한국가시화정보학회지
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    • 제1권1호
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    • pp.98-106
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    • 2003
  • A PLLIF (Planar Liquid Laser Induced Fluorescence) technique has been known to be a useful tool for the measurement of the spray patterns for various spray injectors because it can obtain two-dimensional images with high spatial resolutions without any intrusion on the spray field. In case of dense spray, however, the secondary emission as well as the extinction of an incident laser beam or a fluorescence signal can cause errors in quantifying a mass distribution. Unfortunately, a like-doublet injector which has a dense spray zone at the center may not be a good example or the application of the PLLIF technique. Therefore, we took PLLIF data for the like-doublet injector with a 12 bit color CCD camera by varying laser power, and then assessed their accuracy by comparing with the data obtained with a mechanical patternator and a PDPA (Phase Doppler Particle Analyzer). The experimental results showed that the gray level of fluorescence signal increases nonlinearly due to a secondary emission at the dense spray zone but this nonlinearity can be avoided by reducing the incident laser beam power. In addition, the mass flux distribution of the spray could be obtained by using the mass concentration data from PLLIF technique and the velocity profiles of liquid drops, and this distribution showed good agreement with that of mechanical pattemator. Therefore, it is possible that the PLLIF technique can be successfully applied to finding the mass distributions of like-doublet injectors.

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오리피스 내부유동에 따른 like-doublet 인젝터의 분열 특성 (The Effects of Orifice Internal Flow on the Breakup Characteristics of Liquid Sheets Formed by Like-Doublet Injectors)

  • 정기훈;길태옥;윤영빈
    • 한국분무공학회지
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    • 제7권4호
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    • pp.32-41
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    • 2002
  • The breakup characteristics of liquid sheets formed by like-doublet injector were investigated in the cold-flow and atmospheric ambient pressure condition. The sheet breakup wavelength, which induces the sheet to be broken into ligaments, as well as the sheet breakup length, which is important for the flame location, was measured using a stroboscopic light. The liquid ligaments are formed intermittently after the breakup of sheet, and the wavelength of ligaments has been believed to have a relation to the combustion instability of liquid rocket engine. Therefore, the wavelength of ligaments and the breakup length of ligaments into fine drops were also measured. Since these spray characteristics are affected by the flow characteristics of two liquid jets before they impinge on each other, we focused on the effects of orifice internal flow such as the cavitation phenomenon that occurs inside the sharp-edged orifice. From the experimental results, we found that the liquid jet turbulence delays the sheet breakup and makes shorter wavelengths for both sheets and ligaments. Since the turbulent strength of sharp-edged orifice is stronger than that of round-edged orifice, the shape of orifice entrance results in large differences in the spray characteristics. Using these results, we proposed empirical models on the spray characteristics of the like-doublet injector, and these models are believed to provide some useful and actual data for designing liquid rocket combustors.

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논문 : 액체 로켓의 Like - doublet 인젝터의 충돌 제트 수치 모델에 대한 연구 (Papers : A Study of Numerical Impinging Jet Models for a Like - doublet Injector of Liquid Rockets)

  • 박종훈;정기훈;윤영빈;김영한;이수용
    • 한국항공우주학회지
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    • 제30권3호
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    • pp.64-76
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    • 2002
  • 기존의 이론적 연구와 실험적 연구를 바탕으로 충돌 제트의 수치 모델을 개발하였다. 본 모델은 like-doublet 충돌제트로부터 생성되는 액적의 모든 특성을 액막이 분열되는 시점에서 결정한다. 액적 특성을 결정하기 위해 이론적 연구로부터 얻어진 액막 두께, 액주의 직경, 액적 크기와 실험적 연구로부터 얻어진 액막/액적 속도, 액막 분열 거리, 분열 주파수, 액적 질량 유량 분포를 이용하였다. 액적의 질량 유량 분포는 Laplace 분포로부터 표준 편차를 이용하여 모사하였다. 또한 실험 결과를 이용하여 액막 분열 거리, 분열 주기, 표준 편차에 대한 경험식을 유도하였다. 개발된 모델은 정성적인 분무 패턴뿐만 아니라 정량적인 SMD 및 질량 유량 분포에서 실험 결과와 잘 일치한다.

젤 모사 추진제의 점도 변화에 따른 분무 분열 및 파장 변화 특성 (Breakup Process and Wave Development Characteristics of Gel Propellant Simulants at Various Gelling Agent Contents)

  • 황태진;이인철;김정훈;김도헌;구자예
    • 한국분무공학회지
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    • 제16권3호
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    • pp.140-145
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    • 2011
  • Gelled propellants are non-Newtonian fluids in which the viscosity is a function of the shear rate, and they have a high dynamic shear viscosity which depends on the amount of gelling agent contents. The present study has focused on the breakup process, wave development of ligament and liquid sheets formed by impinging jets with various gelling agent contents. The breakup process of like-on-like doublet impinging jets are experimentally characterized using non-Newtonian liquids. The spray shape with elliptical pattern is distributed in a perpendicular direction to the momentum vectors of the jets. Gelled propellant simulants with high viscosity jets are more stable and produce less pronounced surface waves than low viscosity jets. Gelled propellant simulants from like-on-like doublet impinging jets have the spray shape of closed rim patterns at low pressure. As the injection pressure increased, rimless patterns which were composed of ligament sheets and small droplets emerged due to the effect of the aerodynamic action.

충돌분류에 의한 액적의 크기 및 속도특성에 관한 실험적 연구 (An Experimental study on the drop size and velocity characteristic of drop by impinging jets)

  • 한재섭;김선진
    • 한국분무공학회지
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    • 제4권4호
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    • pp.30-37
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    • 1999
  • The breakup characteristics of liquid sheet formed by the liquid rocket injector has a close relation with the combustion efficiency. In this paper, basic characteristics of droplet size and velocity distribution were measured with PDPA for the Like Doublet Impinging Injector. Test variables were the angle of impact, the diameter of orifice and jet velocity. Water was used as test fluid. As a result, for impingement angle less than 90 degree, following correlations were obtained between drop size and design parameters : $D_{32}({\mu}m)=295.0{\times}V^{-0.09}\times(2\theta)^{-0.1}{\times}d^{0.072}$. For impingement angle greater than 100 degree, drop sizes were increased but eventually converged to a certain limiting value.

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PLIF 기법을 이용한 액체로켓용 충돌분사 인젝터의 분무분포 특성 해석 (Analysis of the Spray Distribution Characterization of Impinging Jet Injectors for Liquid Rockets Using PLIF Technique)

  • 정기훈;윤영빈;황상순
    • 한국추진공학회지
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    • 제4권1호
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    • pp.36-45
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    • 2000
  • 지금까지의 충돌분무에 대한 연구는 제트의 충돌시 형성되는 액막의 분열 과정을 이해하고 이를 모델링하는데 초점을 두어왔기 때문에 실질적으로 연소 효율에 가장 큰 영향을 미치는 연료의 공간분포 특성에 대한 연구가 부족하였다. 따라서 본 연구에서는 like-doublet 충돌분사 노즐을 사용하여 연료 유량 플럭스의 단면분포 특성을 연구하였다. PDPA(Phase Doppler Particle Analyzer)를 통해 액적의 크기를 측정한 기존의 방법은 연료의 평면적인 분포특성을 이해하는데 상당히 제한적이었기 때문에 평면 레이저 유도형광기법(PLE : Planar Laser Induced Fluorescence)을 이용하여 분무의 단면 분포를 측정하였고, 직접사진을 통하여 액적의 크기도 측정하여 PLIF의 결과와 비교하였다.

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기체주입 충돌제트의 분무특성에 관한 실험적 연구 (Experimental Study on the Spray Characteristics of Aerated Impinging Jets)

  • 이근석;윤영빈;안규복
    • 한국분무공학회지
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    • 제24권4호
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    • pp.185-193
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    • 2019
  • The effervescent atomizer is one of twin-fluid atomizers that aeration gas enters into bulk liquid and two-phase flow is formed in the mixing section. The effervescent atomizer requires low injection pressure and small amount of aeration gas, as compared to other twin-fluid atomizers. In this study, cold flow test was conducted to investigate the spray characteristics of aerated impinging jets. The present effervescent impinging atomizers were composed of the aerator device and like-on-like doublet impinging atomizer which had different impinging angles. To analyze the spray characteristics such as breakup length and droplet size distribution, the image processing technique was adopted by using instantaneous images at each flow condition. Non-dimensional parameters, induced by the homogeneous flow model, were used to predict the breakup length. The breakup length was decreased with the mixture Reynolds number and impinging angle increasing. The result of droplets showed that the size distribution was axisymmetric about the center of the injector and their diameter tended to decrease with increasing GLR.

주위 기체밀도와 분사속도에 따른 충돌제트의 미립화 특성 (Effect of ambient gas density and injection velocity on the atomization characteristics of impinging jet)

  • 임병직;정기훈;길태옥;윤영빈
    • 한국항공우주학회지
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    • 제32권6호
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    • pp.104-109
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    • 2004
  • 본 논문에서는 액체로켓 엔진에 많이 사용된 충돌형 분사기의 미립화 특성에 대해 연구하였다. 분사속도와 주위 기체압력은 분열과 미립화 과정에 결정적인 영향을 주는 변수로서 $3m/s{\sim}30m/s,\;0.1Mpa{\sim}4.0MPa$로 변화시키면서 실험을 수행하였다. 전체적으로 분사속도와 기체압력의 증가에 따라 측정된 분열길이, 분열파장, 액적크기 등이 감소하였다. 하지만 그 감소율은 이론에서 예측된 것과는 다른 값을 나타내었다.