• 한국자동차공학회논문집
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• 제2권2호
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• pp.117-123
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• 1994

This paper describes the effect of air assisted fuel injection system(AAI) using compressed air to improve the performance of lean combustion engine. AAI is designed to promote fuel atomization and intake flow. In order to investigate the performance of engine with AAl, experiments are conducted varying the engine revolution speed, lean air-fuel ratio and intake manifold pressure. Compared with the original engine, the performance of the engine with MI is improved as the air-fuel mixture becomes leaner or the engine load becomes lower. The descreasing rate of BSFC is propotional to the relative air-fuel ratio and the lean misfire limit extended more than 0.2 relative airfuel ratio.

• 한국분무공학회지
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• 제3권4호
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• pp.16-24
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• 1998

The fuel injection type, in the gasoline engines of atomization of fuel droplet and its distribution hae influenced directly on the decision of engine performance and harmful emission. In this paper, atomization characteristics of fuel spray is investigated with microscopic visualization system. Particle motion analysis system is used to measure the SMD from fuel spray of air-assisted injector by initial factors such as temperature of ambient air and air-assisted pressure. As air-assist pressure and ambientair temperature increase, the SMD is decreased, and its variation is more stable.

• 대한기계학회논문집
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• 제10권3호
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• pp.367-375
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• 1986

본 연구에서는, 주분무의 착화지연기간에 미치는 보조연료 분사시기의 영향 및 공기유동을 연소장 내에 도입시켜 분무와 공기의 혼합을 적극적으로 촉진시킴에 따라 그 후의 연소과정이 어떤 영향을 받는가에 대해서 검토했다.또 소형고속 디이 젤기관에서는 분무의 연소기간을 최대한 단축 시키지 않으면 안되므로, 보조연료 분사 에 의해 그 단축목적이 어느 정도 달성될 수 있는 가능성을 제2보에서 시사한 바 있으 나 본 연구에서 더욱 상세히 검토했다.

• 한국자동차공학회논문집
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• 제8권4호
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• pp.42-50
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• 2000

Drop size distribution of an air-assisted fuel injector(AAFI) was investigated. Influence of parameters such as ambient air density supply pressure and air-liquid mass ratio(ALR) was examined through both measurement and analysis. The Sauter mean diameter$D_{32}$ varied from 9 to 25$\mu$m throughout all experimental conditions. An empirical correlation for droplet size was obtained. Analytical correlations for predicting $D_{32}$ with respect to operating conditions were also derived through energy consideration and introduction of a simplified model of the from the empirical fitting was adapted to the original equation the proposed correlation in this study matched more closely with measured results. The current correlation exhibited a favorable study matched more closely with measured results. The current correlation exhibited a favorable prediction for $D_{32}$ compared to that by the empirical correlation at selected experimental conditions so that it may be used to predict atomization performance of the AAFI at operating conditions which was not covered in the measurements. After validation the analytical equation was applied to survey the feasible operating conditions for gasoline direct injection application.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.52-58
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• 1998

The spray characteristics of air-assisted fuel injection and its effects on the engine combustion was investigated in this study. The atomization characteristics of a Bosch fuel injector inserted into the air-assist adapter were measured using particle motion analysis system. Droplet size decreased with air supplied and fine spray with below $60\mu\textrm{m}$ of SMD was acquired under the conditions of air-assist pressure over 0.5bar. The lean combustion performance of a 1.8L DOHC engine equipped with air-assist adapters was tested on the dynamometer. When the assistant air pressure is 1.0bar, lean limit recorded the highest value, and CO, HC emissions were decreased at the pressure over 1.0bar.

• 한국자동차공학회논문집
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• 제6권3호
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• pp.187-197
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• 1998

To investigate the spray behavior and atomization characteristics using an air-assist injector, spray visualization and PDPA measurements were carried out under the various assisted air pressures and the fixed fuel pressure. The air assist pintle type injector employed in this study is consisted of the air assist adaptor and an injector housing using the gasoline fuel and air as the working fluids. As results, increasing pressure of assisted air, the growth of spray tip penetration is gradually reduced at the end of spray and spray angle is steadily increased at the main spray region except from the early spray. For the air assist pressure of 25㎪ in a spray downstream, it is doncluded that droplet size distribution shows the peak of 10${\mu}{\textrm}{m}$ and most of the droplet sizes are less than 50${\mu}{\textrm}{m}$. Also, the air-assist injector extremely improves fuel atomization in order to produce much finer droplets, it shows that approximately, in this case, 50% decreade of SMD than without air assit.

• 한국분무공학회지
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• 제3권4호
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• pp.58-64
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• 1998

In the gasoline engine of fuel injection type, atomization of fuel droplet and its distribution has directly influenced the performance of engine and harmful emission. To investigate atomization characteristics of fuel spray, in this paper fuel spray of air-assisted injector is observed at the various initial conditions of ambient air temperature and air assisted pressure. Behavior of fuel spray is photographed with microscopic visualization system. The SMD of fuel droplet is measured with PMAS (Particle Motion Analysis System). The effect of air-assisted pressure and temperature of ambient air resulted in the decrement of SMD and its variation. Finally, It was found that It was found that from spray angle at the two-hole injector had measured $20{\pm}4$ degree the result of photographs by shadow graphy. The mean diameter of suns decreased and the of droplets increased with increasing the temperature in the spray fields by the results of PMAS measurement. It was found that the characteristics of sprays became finer by increasing the temperature of spray fields about 373K without the delivery of air-assistance.

• 대한기계학회논문집B
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• 제23권1호
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• pp.92-103
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• 1999

The fuel spray behavior in the intake port of an electronic control port irijection gasoline engine has a strong influence on engine performance, exhaust emission and fuel consumption. Thus, in this study, fuel spray behavior and flow characteristics of the air assist gasoline spray injected into a suction flow in a simulated rectangular intake port have boon investigated. Macro-behavior of spray characteristics was investigated by means of visualization and the measurements of SMD and velocity were made by PDPA. For analysis the flow field with droplets size, droplets are classified five droplets size groups. As a result, the normal distance of suction flow increasing, the relatively large droplets distribution and SMD increase because small droplets easily follow suction flow. Near impinging wail, after impinging against the wall, secondary atomized small droplets of D < $30{\mu}m$ bound from the wall. And the increasement of suction flow progress to the large droplets of D > $100{\mu}m$ distribution. Therefore, SMD are apparently increased near impinging wall, Z/d = 9.0.

• 대한기계학회논문집
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• 제9권5호
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• pp.627-637
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• 1985

본 논문에서는 종래의 방법을 개량해서 연소과정의 휘도변화를 전기적신호로 변환시키고, 이 전기신호와 연료분사개시기에 발생하는 전기신호와의 시간차를 시간 간격측정기에 의해 계측하는 방법을 택했다. 이 방법에 의해 측정하고저 하는 온도 또는 연료의 종류별로 매 1,000개의 시간차 데이터를 퍼스널.컴퓨터(personal compu- ter)에 기억시켜 통계처리했다.그리고 착화지연기간의 측정결과에 대해서는 보조연 료로서 사용한 유기화합물의 반응성으로 부터 고찰했다.

• 대한기계학회논문집B
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• 제37권12호
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• pp.1079-1089
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• 2013

폐기물을 효과적으로 소각 처리하기 위해, 고형화된 입자를 고속으로 연소시키는 소각로의 유동 특성을 수치해석적으로 조사하였다. 본 연구에서는, 기존 발전소에서 통용되는 선회 유동 유발을 통한 안정적 화염형성 개념과 고에너지 밀도를 갖는 로켓 엔진 연소실의 설계 개념을 복합적으로 적용하였다. 첫단계로, 소각로로 분사되는 연료와 공기의 유동 특성 파악을 위해 1차 연소실에 주 분사기와 보조 분사기를 장착하여 비반응 유동장 수치해석을 수행하였다. 설계 변경 인자로 주 분사기의 편향각, 보조 분사기의 하향각, 두 분사기간 간격을 선정하였다. 이러한 설계 인자의 변경에 따른 선회 유동 형성의 정도를 파악하기 위해 선회수(swirl number)를 평가 인자로 사용하였다. 각각의 설계 인자가 변함에 따라 선회수는 편향각이 증가할수록 선회수가 증가하였으며, 하향각에 따라서는 선회수가 크게 변하지 않았다. 설계 인자에 따라 형성되는 재순환 영역의 크기가 달라지며 이는 선회수의 크기에도 영향을 끼쳤다. 재순환 영역의 크기가 작으면 선회수가 큰 경향성을 보였다. 이러한 수치해석을 통해 활발한 선회 유동을 형성시킬 수 있는 설계 조건을 찾을 수 있었다.