• Title/Summary/Keyword: 원추형 액막

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Prediction of drop size by analysis of conical liquid sheet breakup (원추형 액막분열 해석에 의한 액적 크기 예측)

  • Yoon, S.J.;Cho, D.J.
    • Journal of ILASS-Korea
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    • v.2 no.1
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    • pp.8-17
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    • 1997
  • A study has been carried out on the instability of a conical liquid sheet by using the linear instability theory. Various analytical methods using the Kelvin-Helmholtz instability theory were tried to examine the wave growth on cylindrical liquid sheets. Cylinderical liquid sheets were extended to the case with the conical sheets. Perturbations due to tangential motion as well as longitudinal one were taken into account. And it was assumed the the breakup occurs when amplitude ratio exceeds exp(12), drop sizes were predicted only by theoretical approach. The predicted drop size agreed well with the measured Sauter mean diameter, $D_{32}$.

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Spray Angle of Hollow Cone Liquid Sheet Discharged from Simplex Swirl Spray Nozzle (단순 와류 분무 노즐에서 분사되는 중공 원추형 액막의 분무각)

  • Koh, K.U.;Lee, S.Y.
    • Journal of ILASS-Korea
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    • v.7 no.4
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    • pp.1-8
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    • 2002
  • This paper investigates the spray angle and the outline shape of the liquid sheet discharged from a simplex swirl nozzle. A theoretical model was proposed and the corresponding experimental data were presented for comparison. Axial and tangential velocities and thickness of the liquid sheet at the nozzle exit were also predicted. The liquid sheet thickness at nozzle exit, as well as the discharge coefficient, turned out to be a sole function of the swirl Reynolds number. However, the axial and tangential velocities at nozzle exit and the spray angle could not be expressed only with the swirl Reynolds number. The predicted outline shape and spray angle of the liquid sheet agreed reasonably with the measured data.

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Modeling of Wall Impingement Process of Hollow-Cone Fuel Spray according to Wall Geometry (벽면 형상에 따른 중공 원추형 분무의 벽 충돌 과정 모델링)

  • Shim, Young-Sam;Choi, Gyung-Min;Kim, Duck-Jool
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.3467-3472
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    • 2007
  • The effects of the wall geometry on the spray-wall impingement process of a hollow-cone fuel spray emerging from a high-pressure swirl injector of the Gasoline Direct Injection (GDI) engine were investigated by means of a numerical method. The ized Instability Sheet Atomization (LISA) & Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model for spray atomization process and the Gosman model were applied to model the atomization and wall impingement process of the spray. The calculation results of spray characteristics, such as a spray development process and a radial distance after wall impingement, compared with the experimental ones by the Laser Induced Exciplex Fluorescence (LIEF) technique. It was found that the radial distance of the cavity angle of 90$^{circ]$ after wall impingement was the shortest and the ring shaped vortex was generated near the wall after spray-wall impingement process.

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Spray Breakup Characteristics of a Swirl Injector in High Pressure Environments (고압환경에서 스월 인젝터의 분무 및 분열특성)

  • 김동준;윤영빈;임지혁;길태옥;한풍규
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.7
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    • pp.97-104
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    • 2006
  • The spray and breakup characteristics of swirling liquid sheet were investigated by measuring the spray angle and breakup length as the axial Weber number Wel was increased up to 1554 and the ambient gas pressure up to 4.0MPa. As Wel and ambient gas density increased, the disturbances on the annular liquid sheet surface were amplified by the increase of the aerodynamic forces, and thus the liquid sheet disintegrated near from the injector exit. The measured spray angles according to the ambient gas density were different before and after the sheet breaks. Before the liquid sheet breaks, the spray angle was almost constant, but once the liquid sheet started to breakup, the spray angle decreased. And the breakup length decreased because of the increase of the aerodynamic force as the ambient gas density and Wel increased. Lastly, the measured breakup length according to the ambient gas density and Wel was compared with the result by the linear instability theory. We found that the corrected linear instability theory considering the attenuation of sheet thickness agrees well with our experimental results.