• Title/Summary/Keyword: 수직분사

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A Study on the Characteristics of Liquid Jet in Crossflows Using Elliptical Nozzles (타원형 노즐을 이용한 횡단류 유동에서 액체제트 특성 연구)

  • Song, Yoonho;Hwang, Donghyun;Ahn, Kyubok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.320-324
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    • 2017
  • Effect of elliptical orifice on the spray characteristics of liquid jet ejecting into subsonic crossflows were experimentally studied. Circular/elliptical plain-orifice injectors, which had different ratios of the orifice length to diameter and major axis to minor axis, were used for transverse injection. Compared with the previous research, breakup lengths of elliptical nozzles are shorter than circular nozzles at all experimental condition. Cavitation/hydraulic flip are considered as a reduction in the breakup length at all circular/elliptical nozzle. In the case of liquid column trajectories, major axis which was placed to the crossflows, increases the frontal area of the liquid column exposed to the crossflows. Hence, the aerodynamic force exerted on the jet is increased and the penetration depth is reduced.

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Spray Characteristics of Impinging Injectors in Crossflows (횡방향 유동에서 충돌형 분사기의 액체제트 분무 특성)

  • Song, Yoonho;Lee, Woongu;Ahn, Kyubok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.949-952
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    • 2017
  • Spray characteristics of the impinging injectors in subsonic crossflows were experimentally studied and compared with the plain-orifice injectors. By changing the impingement angle (60, 90, 120) which is the same orifice length to diameter ratio (L/d = 5), spray characteristics were investigated. In the view of the top view from the impinging injectors, as the impingement angle increases, the liquid column breakup length in the y-direction was decreased. On the other hand, when the impinging injector is viewed from the side view, the breakup length in the x direction is smaller than the previous plain-orifice injectors, which mean that the atomizing performance of the impingement-type injector is better than that of the single-hole orifice.

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Spray Plume Characteristics of Liquid Jets in Subsonic Crossflows (수직분사제트의 액적영역 분무특성에 대한 연구)

  • Song Jin-Kwan;Ahn Kyu-Bok;Oh Jeong-Seog;Yoon Young-Bin
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2005.11a
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    • pp.201-206
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    • 2005
  • The effect of internal liquid flow on spray plume characteristics was performed experimentally in subsonic crossflows. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of the research are to investigate the effect of internal liquid flow on the spray plume characteristics and compare the trajectory of spray plume with previous works. The results suggest that the trajectory of spray plume can be correlated as a function of liquid/air momentum flux ratio(q), injector diameter and normalized distance from the injector exit(x/d). It's also found that the injector internal turbulence influences the spray plume characteristics significantly.

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Characteristics of Dual Transverse Injection in Supersonic Flow Fields I-Mixing Characteristics (초음속 유동장 내 이중 수직분사의 특성에 관한 연구 I-혼합특성)

  • Shin, Hun-Bum;Lee, Sang-Hyeon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.6
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    • pp.53-60
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    • 2002
  • Based on the analyses of the single transverse injection in supersonic flow fields, the mixing characteristics of dual transverse injection of hydrogen in supersonic air flow are studied with computational methods. Three-dimensional Navier -Stokes and the k-$\omega$ SST turbulence model were used. A parametric study is conducted with the variation of the distance between two injectors. The flow patterns and the mixing characteristics of two injection flows are very different from each other, and the flow patterns and the mixing characteristics of the rear injection flow are strongly influenced by those of the first injection flow. The increase of the distance between two injectors up to a specific distance results in the increase of mixing rate and penetration of fuel. However, the increase of the distance over the specific distance results in the decrease of mixing rate and penetration of fuel. From the results it can be stated that there exists a distance between two injectors for optimum mixing characteristics.

Verification and Validation of the Numerical Simulation of Transverse Injection Jets using Grid Convergence Index (GCI 를 이용한 수직분사제트 수치모사의 검증 및 확인)

  • 원수희;정인석;최정열
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.4
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    • pp.53-62
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    • 2006
  • Two-dimensional steady flowfields generated by transverse injection jets into a supersonic mainstream are numerically simulated. Fine-scale turbulence effects are represented by a k-${\omega}$ SST two-equation closure model which includes $y^+$ effects on the turbulence model. Solution convergence is evaluated by using Grid Convergence Index(GCI), a measure of uncertainty of the grid convergence. Comparison is made with experimental data and other turbulence models in term of surface static pressure distributions, the length of the upstream separation region, and the penetration height. Results indicate that the k-${\omega}$ SST model correctly predicts the mean surface pressure distribution and the upstream separation length for low static pressure ratios. However, the numerical predictions become less consistent with experimental results as the static pressure ratio increases. All these results are taken within 1% error band of grid convergence.

Spray Characteristics of Liquid Jets in Acoustically-Forced Crossflows (음향가진된 횡단류 유동장 내 액체제트의 분무특성)

  • Song, Yoonho;Hwang, Donghyun;Ahn, Kyubok
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.2
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    • pp.1-10
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    • 2018
  • This study investigated the acoustic forcing effects on the liquid column breakup length and the trajectory of liquid jets in crossflows. Cold-flow tests with a single hole circular nozzle injector were carried out by changing the injection pressure and acoustic forcing amplitude. Additionally, spray images were obtained at 12 phase angles to investigate the influence of the phage angle. The results revealed that the liquid column breakup lengths generally decreased under the acoustic forcing conditions, in comparison to those under the non-acoustic forcing conditions. However, they were not affected by the variation in the phase angles. On the contrary, it was found that the acoustic forcing hardly influenced the liquid column trajectories.

Hexane Vapor Concentration Measurement of a Liquid Jet in Crossflow (수직분사제트에서의 헥산 증기농도측정)

  • Oh, Jeong-Seog;Lee, Won-Nam;Lee, Jong-Geun;Santavicca, Dominique A.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.383-389
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    • 2010
  • The vapor concentration of hexane in a liquid spray jet in crossflow was qualitatively measured on the basis of the infrared (IR) extinction techniques. The objectives of the present study are to understand the whole evaporation process from droplet breakup to vapor and to confirm the usefulness of IR emission method in a lab-scale ramjet combustor. From the experimental results, we concluded that hexane vapor mole fraction increased with temperature rise and kept nearly constant during the variation of fuel to air momentum ratio.

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Spray Plume Characteristics of Liquid Jets in Subsonic Crossflows (수직분사제트의 액적영역 분무특성에 대한 연구)

  • Song, Jin-Kwan;Ahn, Kyu-Bok;Oh, Jeong-Seog;Yoon, Young-Bin
    • Journal of ILASS-Korea
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    • v.11 no.2
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    • pp.113-120
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    • 2006
  • The effect of internal liquid flow on spray plume characteristics was performed experimentally in subsonic cross flows. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of the research are to investigate the effect of internal liquid flow on the spray plume characteristics and compare the trajectory of spray plume with previous works. The results suggest that the trajectory and width of spray plume can be correlated as a function of liquid/air momentum flux ratio(q), injector diameter and normalized distance from the injector exit(x/d). It's also found that the injector internal turbulence influences the spray plume characteristics significantly.

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Hexane Vapor Concentration Measurement of a Liquid Jet in Crossflow (수직분사제트에서의 헥산 증기농도측정)

  • Oh, Jeong-Seog;Lee, Won-Nam;Lee, Jong-Geun;Santavicca, Dominique A.
    • Journal of the Korean Society of Propulsion Engineers
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    • v.14 no.4
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    • pp.25-31
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    • 2010
  • The vapor concentration of hexane in a liquid spray jet in crossflow was qualitatively measured on the basis of the infrared (IR) extinction techniques. The objectives of the present study are to understand the whole evaporation process from droplet breakup to vapor and to confirm the usefulness of IR emission method in a lab-scale ramjet combustor. From the experimental results, we concluded that hexane vapor mole fraction increased with temperature rise and kept nearly constant during the variation of fuel to air momentum ratio.

An experimental study on the structure of the jet flame in cross flow (균일 유동장에 수직으로 분사된 제트화염의 구조에 대한 실험적 연구)

  • 유영돈
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1994.11a
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    • pp.84-89
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    • 1994
  • 주유동에 수직으로 분사된 제트 화염의 구조는 이해하기 위하여 화염 길이와 온도를 측정하고 reactive mie scattering 방법을 이용하여 단면 가시화를 실시하였다. 주유동 속도와 제트 분사 속도의 증가에 따라 화염 길이도 함께 증가함을 알 수 있고, 단면 가시화 결과 화염 내부에 존재하는 inner vortical structure는 일반적인 동축제트 화염과 같은 대칭 구조를 갖지 앉고 유동 조건에 따라 inner vortical motion 의 생성 위치가 변화함을 알 수 있다 이는 본 유동장의 특성 중의 하나인 bound vortex와 제트와 주유동이 접하는 상류 면에서 발생하는 rolling-up 의 강도에 좌우됨을 알 수 있다.

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