• 한국자동차공학회논문집
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• 제3권6호
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• pp.123-133
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• 1995

An injection control valve(ICV) was designed to control the fuel flow between a common rail and an injector with two commercial solenoids. To improve the performance of ICV, the characteristic method was applied. With this method, the flow characteristics in the ICV and the injector were studied and the parameters which affect the injection characteristics were also studied. From this study, following results were obtained. The injection duration can be controlled and with modifications of the effective valve stroke of ICV, the injection quantity and duration can be reduced to desired amount. Also the injection quantity and pressure can be controlled by reducing the hole size of the injector without the variation of the injection duration. For some conditions, the desired injection characteristics can be obtained by the changes of the valve timing, the effective valve stroke, the open pressure of the injector and the hole size of the injector.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 추계 학술대회논문집
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• pp.17-22
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• 2002

A numerical solution procedure has been developed to analyze the flow field resulted from the injection of a transverse jet through the divergent flap of a 2DCD nozzle for thrust vector control. The formulation employs the compressible Navier-Stokes equations in conservation law form and a two equation $\kappa-\omega$ turbulence model. Detailed numerical results are presented in this paper for the 2DCD nozzle over a range of secondary to primary injection mass flow ratios and nozzle pressure ratios.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제13권1호
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• pp.1-10
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• 2006

The unsteady Hartmann flow of an electrically conducting, viscous, incompressible fluid bounded by two parallel non-conducting porous plates is studied with heat transfer. An external uniform magnetic field and a uniform suction and injection are applied perpendicular to the plates while the fluid motion is subjected to a constant pressure gradient. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of the magnetic field and the uniform suction and injection on both the velocity and temperature distributions is examined.

• 한국산학기술학회논문지
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• 제7권3호
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• pp.471-475
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• 2006

랩온어칩(Lab-on-a-chip) 등 미세구조를 갖는 다양한 장치들의 대량 생산이 가능한 사출성형공정 내에서의 미세 흐름 거동의 이해는 매우 중요하다. 본 논문에서는 마이크로 채널 구조 내에서의 사출성형 흐름에 관하여 연구하였다. 흐름 현상을 관찰하기 위하여 투명한 PMMA를 사용하여 가시화 금형(visual mold)을 제작하였다. 실험 대상 물질로는 고분자 용액인 PEO (poly (ethylene oxide)) 와 PA (polyacrylamide) 용액을 선정하였는데, 이는 고분자 용융체의 특징인 높은 점성과 탄성을 갖도록 설계한 것이다. 시간에 따른 흐름현상과 주 채널과 마이크로 채널과의 경쟁적인 흐름 현상을 관찰하였다. 이로부터 마이크로 사출성형 흐름에서 나타나는 마이크로 채널 내의 충전길이에 대한 해석이 가능하였다.

• 대한기계학회논문집B
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• 제26권12호
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• pp.1655-1662
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• 2002

Recently, many researches have been performed to improve the performance of the combustion and emission in a D.I.Diesel engine. And many new techniques have been introduced and developed to reduce NO$_{x}$ and soot exhausted from diesel combustion. Some of these methods have the peculiar injection timing which is not used to traditional timing. To optimize these injection timing, characteristics of swirl flow and interaction of swirl with injection in the diesel engine should be investigated more carefully. Therefore, in this study, 2-zone energy method is adopted for the understanding of swirl flow in condition of moving piston, and then flame visualizations and image process are performed. From these studies, the characteristics of the swirl flow generated by SCV was investigated and the effect of swirl on injection timing was elucidated. As the results, velocity distribution caused by swirl flow increase the space utilization rate of flame plums. And flame plums of weak momentum are remained inside of combustion chamber by the swirl flow.w.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.23-30
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• 2002

This present study experimentally investigates the behavior of liquid and vapor phase of fuel mixtures with changing the in-cylinder air motion in an optically accessible engine. The conventional MPI/DOHC engine was modified to gasoline direct injection engine with swirl motion. The images of liquid and vapor phases were captured in the motoring operation condition using exciplex fluorescence method. Two dimensional spray fluorescence images of liquid and vapor phases were acquired to analyze spray behaviors and fuel distribution inside of cylinder respectively, In early injection timings $(BTDC\;270^{\circ},\;180^{\circ})$, tumble flow transported most of vapor phase to the lower region and the both sides of cylinder, so vapor phase didn't become uniform distribution up to the half of the compression stroke. In the case of swirl flow, the fuel mixture was confined near the swirl origin in upper region of cylinder. In late injection timings $(BTDC\;90^{\circ})$, tumble flow transported vapor phase to the intake valve and swirl flow to the exhaust valve.

• 한국분무공학회지
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• 제20권1호
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• pp.43-52
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• 2015

Experimental study was conducted to investigate the effects of ultra-high injection pressure and nozzle hole diameter on diesel flow and spray characteristics. Electronically controlled ultra-high pressure fuel injection system was made to supply the fuel of ultra-high pressure consistently. Three injection pressures, 80, 160, and 250MPa were applied. Four type of injectors with identical eight nozzle holes were used. The four injectors have nozzle hole diameters of 115, 105, 95, and $85{\mu}m$ respectively. Injection quantity and rate were measured to investigate flow characteristics according to injection pressures and nozzle hole diameters. Mie-scattering and shadowgraph were performed to visualize liquid and vapor phases of diesel spray in a constant volume combustion chamber (CVCC). Ambient conditions of high pressure and high temperature in a diesel engine were simulated by using CVCC.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.214-219
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• 2002

As the tangential flow inside the clearance of tribe elements such as bearings and seals is increased as the shaft speed increases, the system stability will be decreased due to the increment of the instability parameter. To reduce the tangential flow inside the clearance of the balance sleeve, anti-swirl injection mechanism is applied. The balance sleeve is used in resisting the axial force induced by impeller in high pressure multi-stage pump. In this paper, total three cases are experimentally investigated; original balance steeve, anti-swirl injection balance steeve with 0 axial degree and anti-swirl injection balance sleeve with 30 axial degree. Experiments are focused in the comparison of vibration level and leakage flow rate. The results clearly shows that the anti-swirl injection balance sleeve with 0 axial degree improves the vibration characteristics. However, the anti-swirl injection balance sleeve with 30 degree aggravates the vibration characteristics. In the standpoint of leakage performance, both anti-swirl injection balance sleeves show the better result than the original balance sleeve.

• 항공우주기술
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• 제10권1호
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• pp.129-135
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• 2011

본 연구는 중앙 물분사 방식을 채택한 액체로켓엔진 후류의 냉각에 대해 전산유체역학을 통한 특성을 고찰하였다. 중앙 물분사 방식의 냉각은 측면 물분사 방식과는 달리, 잘 알려져 있지 않기 때문에 다양한 물분사량과 유량을 통해 효율적으로 후류를 냉각시킬 수 있는 조건을 찾았으며, 해석을 통해 후류의 변화 특성을 살펴보았다. 이로부터 물분사 유량이 총추진제 유량의 2배 이상, 위치는 L/De=1.2일 때가 적당함을 알 수 있었다.

• 한국소음진동공학회논문집
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• 제12권8호
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• pp.632-638
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• 2002

As the tangential flow inside the clearance of tribo elements such as bearings and seals is increased as the shaft speed increases, the system stability will be decreased due to the increment of the instability parameter. To reduce the tangential flow inside the clearance of the balance sleeve, anti-swirl injection mechanism is applied. The balance sleeve is used in resisting the axial force induced by impeller in high pressure multi-stage pump. In this paper, total three cases are experimentally investigated; original balance sleeve, anti-swirl injection balance sleeve with 0 axial degree and anti-swirl injection balance sleeve with 30 axial degree. Experiments are focused in the comparison of vibration level and leakage flow rate. The results clearly shows that the anti-swirl injection balance sleeve with 0 axial degree improves the vibration characteristics. However, the anti-swirl injection balance sleeve with 30 degree aggravates the vibration characteristics. In the standpoint of leakage performance, both anti-swirl injection balance sleeves show the better result than the original balance sleeve.