• Title/Summary/Keyword: Ejection angle

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Effect of Outer Nozzle Ejection Angle on Jet Structure issuing from Supersonic Dual Coaxial Nozzle (초음속 동축 제트의 구조에 미치는 외부노즐 분사각의 영향)

  • Baek, Seung-Cheol;Kwon, Soo-Young;Joo, Seong-Yeol;Kwon, Soon-Bum
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.426-431
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    • 2001
  • This paper experimentally investigates the characteristics of dual coaxial jet issuing from inner supersonic nozzle and four kinds of outer converging nozzle of 40, 50, $60^{\circ}$ and $70^{\circ}$ in outer ejection angle. The pressure ratio of the stagnation to the exit ambient pressures in the inner supersonic nozzle of constant expansion rate is 7.5, which is corresponded to the condition of a slightly underexpanded, and that of outer nozzle is 4.0. Flow visualizations by using of shadowgraph method, impact pressure and centerline static pressure measurements are presented. It is found that the jet structure is changed significantly by the variation of outer nozzle ejection angle. Impact pressure level is lower and undulation of static pressure is higher, as the injection angle of outer jet increases.

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An Experimental Study of Supersonic Dual Coaxial Free Jet

  • Baek, Seung-Cheol;Kwon, Soon-Bum;Lee, Byeong-Eun
    • Journal of Mechanical Science and Technology
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    • v.17 no.12
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    • pp.2107-2115
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    • 2003
  • A supersonic dual coaxial jet has been employed popularly for various industrial purposes, such as gasdynamic laser, supersonic ejector, noise control and enhancement of mixing. Detailed characteristics of supersonic dual coaxial jets issuing from an inner supersonic nozzle and outer sonic nozzles with various ejection angles are experimentally investigated. Three important parameters, such as pressure ratios of the inner and outer nozzles, and outer nozzle ejection angle, are chosen for a better understanding of jet structures in the present study. The results obtained from the present experimental study show that the Mach disk diameter becomes smaller, and the Mach disk moves toward the nozzle exit, and the length of the first shock cell decreases with the pressure ratio of the outer nozzle. It was also found that the highly underexpanded outer jet produces a new oblique shock wave, which makes jet structure much more complicated. On the other hand the outer jet ejection angle affects the structure of the inner jet structure less than the pressure ratio of the outer nozzle, relatively.

Ground Ejection Tests for the Safe Separation Analysis of a Gliding Bomb (활공탄의 안전분리 해석을 위한 지상투하시험)

  • Lee, Kidu;Lee, Inwon;Park, Youngkun;Baek, Seungwoock;Jung, Nahyeon;Jung, Sangjun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.6
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    • pp.502-508
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    • 2013
  • Various combinations of cartridge and orifice were applied for ground ejection tests of a gliding bomb model equipped with a new guidance kit. Larger diameter of orifice made larger ejection force at each of bomb racks. Normal operations of the wing deploying mechanism and the devices inside of the bomb model were confirmed. Also high speed video data showed that pitch angle of the gliding bomb varied due to the ejection force.

Performance Analysis of an Axial Flow Turbine Stage with Coolant Ejection from Stator Trailing Edge (정익 후연의 냉각유체분사를 포함한 축류터빈단의 성능해석)

  • Kim, Tong Seop;Kim, Jae Hwan;Ro, Sung Tack
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.7
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    • pp.831-840
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    • 1999
  • In this work, an aerothermodynamic calculation model for cooled axial flow turbine blades with trailing edge ejection is suggested and a mean line performance analysis of a turbine stage with nozzle cooling is carried out. A unique model regarding the interaction between coolant and main gas is proposed, while existing correlations are adopted to predict viscous loss and blade outflow angle. The interactions considered are the heat transfer from main gas to coolant and the temperature and pressure losses by the mixing of two streams due to the trailing edge coolant ejection. For a stator blade without ejection, trailing edge loss calculated by the trailing edge analysis is compared with that calculated by loss correlation. The effect of heat transfer effectiveness of coolant passage on the mixing loss is analyzed. For a model turbine stage with nozzle cooling, parametric analyses are carried out to investigate the effect of main design variables(coolant mass flow ratio, temperature and ejection area) on the stage performance.

A Study on the Film-cooling Characteristics of Gas Turbine Blade with Various Area Ratios and Ejection Angles of the Double Jet Holes (이중분사 홀의 면적비와 분사각 변화에 따른 가스터빈 막냉각 특성 연구)

  • Cho, Moon-Young;Lee, Jong-Chul;Kim, Youn-Jea
    • The KSFM Journal of Fluid Machinery
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    • v.17 no.3
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    • pp.59-64
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    • 2014
  • The kidney vortex is the important factor adversely influencing film cooling effectiveness. In general, double jet film-cooling hole is designed to overcome the kidney vortex by generating anti-kidney vortices. In this study, the film cooling characteristics and the effectiveness of the double jet film cooling hole were numerically investigated with various area ratios of the first($A_1$) and second($A_2$) cooling hole($A_1/A_2$=0.8, 1.0, 1.25) and lateral ejection angle(${\alpha}$ = $30^{\circ}$, $45^{\circ}$, $60^{\circ}$) as the design parameters. The effects of lateral distance between the first and second row holes are investigated. Numerical study was performed by using ANSYS CFX with the shear stress transport(SST) turbulence model. The film cooling effectiveness and temperature distribution were graphically depicted with various flow and geometrical conditions.

Numerical Study on a Thin Film Patterning Process Using Microdroplet Ejection (미세액적의 분사를 이용한 박막 패터닝 공정에 대한 수치적 연구)

  • Suh, Young-Ho;Son, Gi-Hun
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.658-659
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    • 2008
  • Numerical simulation is performed for a microdroplet deposition on the pre-patterned micro-structure. The liquid-air interface is tracked by level set method improved by incorporating the ghost fluid approach based on a sharp-interface representation. The method is further extended to treat the contact angle condition at an immersed solid surface. The present computation of a patterning process using microdroplet ejection demonstrates that the multiphase characteristics between the liquid-gas-solid phases can be used to overcome the patterning error.

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The Study on the Fragment Ejection Velocity and Spray Angle from a High Explosive Cylindrical Warhead (실린더형 HE 탄두 폭발 시 파편의 속도 및 발사각 추정방법 연구)

  • Hwang, Changsu;Park, Younghyun;Park, Seikwon;Jung, Daehan;Lee, Moonsik;Kang, Sunbu;Kim, Deuksu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.12
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    • pp.904-912
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    • 2019
  • We have studied the numerical analysis about the fragment ejection velocity and spray angle when the High Explosive warhead detonated at proximity distance at an aircraft. To study the physical quantities about the warhead components is very important to assessment the vulnerability of aircraft. Generally, the physical quantities about the components of a warhead such as the mass, length, diameter and charge to mass ratio are unknown. Therefore, it is required to estimate the physical quantities by using physical continuities of similar threats. The empirical formulas to understand the dependence among charge to mass ratio, length and diameter ratio were driven by using the physical parameters of similar threatening such as terrier, sparrow. As a result, we confirmed that the dead mass ratio was closed to 20% of warhead mass since the metal case of the proximity threat acts as a simple carrier. This implies that the effective length and diameter of High Explosive Compound is smaller than the length and diameter of warhead, and become a key to understand the large ejection gradient velocity and small spray angle of fragments within 6 degree.

A NUMERICAL STUDY ON A THIN FILM MANUFACTURING PROCESS USING THE CONTROL OF SURFACE ENERGY OF A MICRODROPLET (미세액적의 표면에너지 제어를 통한 박막 제조 공정에 대한 연구)

  • Suh, Y.;Son, G.
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03a
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    • pp.221-226
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    • 2008
  • Numerical simulation is performed for microdroplet deposition on a pre-patterned micro-structure. The level-set method for tracking the liquid-gas interface is extended to treat the immersed (or irregular-shaped) solid surface. The no-slip condition at the fluid-solid interface as well as the matching conditions at the liquid-gas interface is accurately imposed by incorporating the ghost fluid approach based on a sharp-interface representation. The method is further extended to treat the contact angle condition at an immersed solid surface. The present computation of a patterning process using microdroplet ejection demonstrates that the multiphase characteristics between the liquid-gas-solid phases can be used to improve the patterning accuracy.

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A NUMERICAL STUDY ON A THIN FILM MANUFACTURING PROCESS USING THE CONTROL OF SURFACE ENERGY OF A MICRODROPLET (미세액적의 표면에너지 제어를 통한 박막 제조 공정에 대한 연구)

  • Suh, Y.;Son, G.
    • 한국전산유체공학회:학술대회논문집
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    • 2008.10a
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    • pp.221-226
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    • 2008
  • Numerical simulation is performed for microdroplet deposition on a pre-patterned micro-structure. The level-set method for tracking the liquid-gas interface is extended to treat the immersed (or irregular-shaped) solid surface. The no-slip condition at the fluid-solid interface as well as the matching conditions at the liquid-gas interface is accurately imposed by incorporating the ghost fluid approach based on a sharp-interface representation. The method is further extended to treat the contact angle condition at an immersed solid surface. The present computation of a patterning process using microdroplet ejection demonstrates that the multiphase characteristics between the liquid-gas-solid phases can be used to improve the patterning accuracy.

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A Numerical Study on Patterning Process Including a Self-Alignment Technique of a Microdroplet (미세액적의 자기정렬 기법을 포함한 패터닝 공법에 대한 해석적인 연구)

  • Suh, Young-Ho;Son, Gi-Hun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.1
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    • pp.28-38
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    • 2009
  • Numerical simulation is performed for microdroplet deposition on a pre-patterned micro-structure. The liquid-air interface is tracked by a level-set method, which is improved by incorporating a sharp-interface modeling technique for accurately enforcing the matching conditions at the liquid-gas interface and the no-slip condition at the fluid-solid interface. The method is further extended to treat the contact angle condition at an immersed solid surface. The present computation of a patterning process using microdroplet ejection demonstrates that the multiphase characteristics between the liquid-gas-solid phases can be used to improve the patterning accuracy.