• 한국분무공학회지
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• 제1권4호
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• pp.24-31
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• 1996

This study addresses the behavior characteristics of diesel spray injected on the impinging disk with the room temperature. The models of impinging spray are the stick, the reflect and the wall jet model In the initiative of the fuel injection the impinging spray was the reflect model. because the momentum of droplets was very large. This model developed to the wall jet model according to the time approaches. On the low temperature disk the fuel film was made by the attachment of the droplets with low Weber number. The thickness of impinging spray was increased when the disk approached to the nozzle tip. Mathematical analysis for calculation with the behavior of impinging spray have to consider the reflecting effect and the influence of the fuel film.

• 한국자동차공학회논문집
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• 제3권2호
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• pp.146-156
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• 1995

Growing international concern about environmental issues in recent years has led to new proposals for strengthening exhaust emission standards and fuel economy requirements throughout the world. The low emission vehicle(LEV) standards drawn up by the California Air Resources Board(CARB) in the U.S.A are noticeably stringent To cope with this regulation, a reduction of HC emission is the most important challenge for the automotive industry because HC emission levels are severer than any other components emission levels. In this paper, the apparatus for visulalizing the wall film flow in a intake manifold and the spark plug with optical fiber for detecting the signal from diffusion flame are developed to mal,e the HC formation mechanism clear. High speed camera system is also used to elucidate the correlation wall film flow and the diffusion flame. Using these methods, the effect of fuel injection systems such as injection direction, spray angle, atomised injection on HC emission levels is investigated. Consequently, the optimal fuel injection conditions for minimizing the wall film flow and reducing the HC emission are found through this research.

• 한국항공우주학회지
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• 제31권8호
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• pp.69-76
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• 2003

액체로켓 연소기 내의 막냉각 특성 분석을 위한 비회체 분무연소에 대한 수치해석을 수행하였다. 막냉각 연료의 특성에 따른 연소기 벽면의 온도변화를 살펴보기 위하여 막냉각용 연료의 유랑, 막냉각용 액적의 직경, 그리고 공기/연료 혼합비를 매개변수로 한 수치해석을 수행하여 연소기 벽면의 온도는 막냉각용 연료 액적 직경의 변화에는 큰 영향을 받지 않지만 막냉각용 연료 유량 및 공기/연료 혼합비에 영향을 받고 있음을 확인하였다. 또한, 추진기관 벽면으로 전달되는 전도 및 복사열유속을 고찰함으로서 이러한 액체 추진기관의 연소특성을 이해하기 위해서는 열복사 및 물성치의 적절한 고찰이 필요함을 지적하였다.

• 한국분무공학회지
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• 제1권2호
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• pp.33-41
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• 1996

Mixture formation is one of the important factors to improve combustion performance of MPI gasoline engines. This is affected by spray and atomization characteristics of injector. Especially, in the case of EGI system, air-fuel mixing period is too short and formed a lot of fuel-film in the intake manifold and cylinder wall. This fuel-film is not burnt in cylinder, it is exhausted in the form of HC emission. In this paper, spray characteristics such as size distributions, SMD, and spray angle are measured by PMAS, and the fuel-film measuring device is developed specially. Using this device, the amount and distribution of fuel-film which flows into through valve can be measured Quantitatively. As the result of these experiments, the information of optimal spray characteristics and injection condition that minimize the fuel-film can be built up.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.919-924
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• 2000

Spray impingement model and fuel film formation model were developed and incorporated into the computational fluid dynamics code, STAR-CD. The spray/wall interaction process were modelled by considering the change of behaviour with surface temperature condition and fuel film formation. We divided behaviour of fuel droplets after impingement into stick, rebound and splash using Weber number and parameter K. Spray impingement model accounts for mass conservation, energy conservation and heat transfer to the impinging droplets. A fuel film formation model was developed by Integrating the continuity, the Navier-Stokes and the energy equations along the direction of fuel film thickness. The validation of the model was conducted using diesel spray experimental data and gasoline spray impingement experiment. In all cases, the prediction compared reasonably well with experimental results. Spray impingement model and fuel film formation model have been applied to a direct injection diesel engine combustion chamber.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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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.

• 한국군사과학기술학회지
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• 제9권1호
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• pp.117-124
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• 2006

Experiments on film cooling were performed with a small scale rocket engine homing liquid oxygen (LOx) and Jet A-1(jet engine fuel). Film coolants(Jet A-1 and water) were injected through the film cooling injector. Film cooled length and the outside wall temperature of the combustor were determined for chamber pressure, and the different geometries(injection angle) with the flow rates of film coolant. The loss of characteristic velocity due to film cooling was determined for the case of film cooling with water and Jet A-1. As the coolant flow increases, the outside wall temperatures decrease but the decrease in the outside wall temperatures reduced over the 8 percent film coolant flow rate. The efficiency of characteristic velocity was decreased with the Increase of the film coolant flow rate.

• 한국분무공학회지
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• 제2권4호
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• pp.15-21
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• 1997

In a gasoline engine with port injection system, the fuel behavior in the intake port has significant influence on the HC emission and the precise A/F control. That is to say, it is inevitable that the injection direction and behavior of fuel injected in the intake port have an effect on the generation of unburned HC within a cylinder. In this paper, we visualized fuel behavior in the intake port using micro CCD camera synchronized with the stroboscope and investigated the fuel-film characteristics formed at the wall of intake port by processing image captured with VCR in the transparent intake port made of acryl. Using these measuring methods, it was found that fuel behavior and the formation of fuel-film in the intake port could be evaluated qualitatively. And results obtained by these methods show that 2-spray injector minimizes the fuel-film formed in the intake port of a DOHC gasoline engine.

• 한국분무공학회지
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• 제2권1호
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• pp.36-45
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• 1997

A spray-wall impingement model for fuel sprays is proposed and implemented as a module into the KIVA-POSTECH code. The model is based on the single droplet experiments. The droplet behaviors after impingement are determined from experimental correlations. Different behaviors of impinged droplets depend on the wall temperature and the critical temperature of the fuel. Fuel film formation is taken into account so that the model can be applicable to any wall temperature and injection conditions. Computational results on a normal and on inclined wall are in good agreement for the spray shape and penetration. More validation against experiments and development of the heat transfer model are needed for further improvement.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.210-219
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• 2014

The MPI dual injection engine can enhance the fuel efficiency and engine power. By using one injector per one intake port, MPI dual injection engine has an excellent fuel atomization and targeting injection. As the basic research for the MPI Dual injection engine design, this research was investigated in order to understand the characteristic of the in-cylinder flow and fuel behavior according to engine temperature condition and the fuel type in the MPI dual injection engines. The 3D unsteady CFD simulation for the MPI Dual injection engine was performed using STAR-CD. The engine operating condition was 2,000 rpm/WOT. The parameters for this study were fuel types, fuel temperatures and wall temperatures. As a result, the intake air amount, evaporated fuel in the cylinder and the fuel film on the wall were presented according to parameters that depend on the fuel properties and engine wall temperature. Also, the results were influenced by in-cylinder flow such as the intake flow, back flow and so on.