• 한국분무공학회지
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• 제14권1호
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• pp.8-14
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• 2009

This paper present the diesel fuel spray evolution and atomization performance in a multi-hole nozzle in terms of injection rate, spray evolutions, and mean diameter and velocity of droplets in a compression ignition engine. In order to study the effect of split injection on the diesel fuel spray and atomization characteristic in a multi-hole nozzle, the test nozzle that has two-row small orifice with 0.2 mm interval was used. The time based fuel injection rate characteristics was analyzed from the pressure variation generated in a measuring tube. The spray characteristics of a multi-hole nozzle were visualized and measured by spray visualization system and phase Doppler particle analyzer (PDPA) system. It was revealed that the total injected fuel quantities of split injection are smaller than those of single injection condition. In case of injection rate characteristics, the split injection is a little lower than single injection and the peak value of second injection rate is lower than single injection. The spray velocity of split injection is also lower because of short energizing duration and small injection mass. It can not observe the improvement of droplet atomization due to the split injection, however, it enhances the droplet distributions at the early stage of fuel injection.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.112-120
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• 2005

The injector, which is used in a 4-valve gasoline engine, is required to be maintained the dual stream because of the design of dual intake port. In addition, the spray characteristics of fuel injector have strong influence on engine performance, exhaust emission, fuel consumption, and especially the cold start condition for the port injection. So, commercial gasoline injectors off different type were inspected. Those are 2 hole,4 hole, air shroud 4 hole, and air shroud 4 hole injector with separator. The spray behavior of dual stream was researched by the visualization system and PDPA system was employed to measure the droplet size. Atomization is one of the most important characteristic, so droplet size distributions and SMD are investigated. And the spray characteristics of each injector are also analyzed such as the spray tip penetration, spray angle, and separation angle.

• 한국지반공학회논문집
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• 제19권3호
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• pp.23-31
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• 2003

지난 반세기 동안 검측공 탄성파시험은 시험 장비 및 그 배치에 따라 크로스홀, 다운홀, 서스펜션로깅과 같은 시험으로 발전하였다. 이런 현장시험은 장비와 시험기법이 꾸준히 개선되어 지반 및 지진공학 분야의 부지특성규명에 매우 값진 기술이 되었다. 그러나 이 기술은, 공학적 의의와 중요성에도 불구하고, 표준관입 시험처럼 실무에 보편적으로 적용되지 못하고 있다. 그 이유는 장비가 복잡 정교할 뿐만 아니라, 사용하기 어렵고 비싸기 때문이다. 이 연구에서는 경제적이고 실용적인 지반의 동적물성치 계측 기술 개발을 목표로 하여 인홀 시험법을 연구하였다. 이 연구에서 개발한 인홀장비 시작품은 NX 크기의 검측공에 사용하고 맨손으로 다룰 정도로 작고 가볍다. 이 장비의 발진장치는 여러 현장에서 크로스홀시험을 통하여 그 성능을 검증하였고 꾸준히 개선되고 있다. 세 현장에서 인홀시험을 수행하고 그 결과를 크로스홀시험 결과와 비교하여 타당성을 검증하였다.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.56-62
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• 1999

The disintegration of transient diesel spray in early was investigated at different opening pressure and chamber pressure by measns of shadowgraph method using nanolite and still camera. Diesel spary was injected into the spray chamber which was charged with high pressure nitrogen gas. Atthe begining of injection, a liquid column that was almost the same diameter as the nozzle hole was observed . Spray tip penetration and spray angle were always increased with an increase in opening pressure.

• 한국연소학회지
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• 제4권1호
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• pp.117-129
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• 1999

A method for the mixing augmentation of the transverse injection of fuel in a Scramjet combustor is suggested. Based on the fact that the main factor controlling the mixing characteristics in transverse injection is the effective back-pressure (the pressure around the injection hole) it is tried to make a flow expansion near the injection port in order to reduce effective back-pressure. A three dimensional Navier-Stokes code adopting the upwind method of Roe#s flux difference splitting scheme is used. The k-w SST turbulence model turbulence model is used to calculate the turbulent viscosity. It is shown that the reducing of the effective back-pressure make it possible to increase the penetration distance and to increase the mixing rate without excessive losses of stagnation pressure. Also, it is shown that the streamwise vorticity generated by baroclinic torque has great influences on the mixing process.

• 동력기계공학회지
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• 제14권6호
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• pp.5-12
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• 2010

In this study, an analysis of evaporative diesel spray and an usefulness of a general-purpose program, ANSYS CFX release 11.0, are investigated through the comparison and investigation of the experimental results carried out under an evaporative field, in which there is phase transition, by an exciplex fluorescence method and the results analyzed by the CFX program. The diesel fuel called n-Tridecane, $C_{13}H_{28}$, is injected from a single-hole nozzle (l/d=1.0mm/0.2mm) into a constant volume chamber under a high temperature and pressure. In the same condition as the experimental condition, the analysis was carried out. Both results of the spray tip penetration were almost coincident at each time. The results have validated the usefulness of this analysis. As a result, if the ambient pressure is high, the spray tip penetration will be shortened and move toward the nozzle exit.

• 대한기계학회논문집B
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• 제22권8호
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• pp.1132-1140
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• 1998

The disintegration process of initial spray from high-pressure swirl injector was investigated at different injection pressures. The transient breakup phenomena that were difficult to observe at high injection pressure were easily observed at the low injection pressure of 0.4MPa. The effect of fuel remained inside a nozzle hole volume on the penetration of initial spray was also investigated. The disintegration process of initial spray could be classified four regions: the formation of mushroom shape, the first collision, the second collision, and the development of spray, The liquid film of cup shape was particularly found in the second collision region, and the growth ratio of its length and width at low and high injection pressures were compared.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.161-170
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• 2006

Bender elements, composed of thin piezo-ceramics and elastic shims, have been used to measure shear wave velocities of specimens in laboratories. In a preliminary stage of their field applications, an in-house research of optimizing suitable bender elements and geometrical arrangement has been carried out in a barrel of kaolinite-water mixture. Two types of measurement configuration, similar to cross-hole and in-hole seismic testing, has been implemented. A pair of prototype instrumented rods was penetrated into a soft clay layer in the west coast and excellent shear waves were recorded. Development of penetration device(mandrel) and associated instrumented rods are in progress for deeper investigation.

• 한국분무공학회지
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• 제3권3호
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• pp.42-48
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• 1998

This study describes the spray structure of gasoline port injectors by using phase Doppler particle analyzer(PDPA) and particle motion analysis system(PMAS). The characteristics of fuel spray such as the spray penetration, spray angle and breakup processes were obtained by PMAS and the droplet size and mean velocity were measured by PDPA system. Pintle type and two-hole type injectors were used as gasoline port fuel injectors under various injection pressures. The effect of injection pressure on the droplet mean diameter and axial mean velocity of droplet were investigated under the various injection conditions. In addition the comparison of breakup processes for the two types of injectors was also conducted. It Is shown that pintle type injector has smaller droplet size than that of two-hole type injector.

• 한국안전학회지
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• 제4권1호
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• pp.59-70
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• 1989

This paper deals with the experimental study on the flow characteristics in straight flow can type combustor which has been used for high pressure ratio gas turbine combustor. The author has investigated the effects of swirl number and secondary air hole arrays in axial position on the flow characteristics by adopting the tuft method and 5-Hole Pilot Tube. From these experiments, as the swirl number increases, the results obtained is that the area of recirculation zone becomes wide and the position of vortex-core region approaches to the near of fuel nozzle in the model combustor. The most favourable penetration is obtained when secondary air jet is introduced through the air holes distributed in the form of paralled two rows in axial position of model combustor.