• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.1
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• pp.57-62
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• 2001

EFI system has severe problems of heavy HC emission generated by large fuel droplets and non-uniform air-fuel mixture. Therefore, various atomization techniques are being developed in order to reduce HC emission. The one among those techniques is ar shrouded injector, which has better atomization ability and demands less power loss than other atomizers. Thus, the development of this air shrouded injector can be major topic to cope with international emission regulation. Nevertheless, there are few domestic and foreign studies which deal with air shrouded injector. In this study, the spray characteristics and atomization mechanism of the representative air shrouded injector were analyzed using PDPA system. From experimental results, the definite standards of air shrouded injector's spray characteristics were established.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.11a
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• pp.82-90
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• 2000

Improving the atomization characteristics by adopting the Air-Shrouded injector has been considered as one of the important methods for decreasing HC emissions in SI engines. Thus, in this study for the purpose of developing Air-Shrouded injector which has a finer spray, atomization characteristics of different types of commercial Air-Shrouded injectors were investigated through the spray imaging and the drop size measurements. As a result, it was found that the internal mixing type of Air-shrouded injector had a good atomization characteristics. But, a number of large droplets were found in the internal mixing type commercial injector, this phenomenon was improved by adopting the thread type nozzle passages.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.4
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• pp.912-919
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• 2001

Improvement of the atomization characteristics by adopting the air-shrouded injector has been considered as one of the important methods for decreasing HC emissions in SI engines. Thus, in this study to develop air-shrouded injector with a finer spray, atomization characteristics of differ-ent types of commercial air-shrouded injectors were investigated through the spray imaging and the drop size measurements. As a results, it was found that the internal mixing type of air-shroud-ed injector had a good atomization characteristics. But, a number of large droplets were found in the internal mixing type commercial injector, this shortcoming was improved by adopting the thread type air passages in the air nozzle.

• Journal of ILASS-Korea
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• v.5 no.2
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• pp.68-74
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• 2000

A this experimental study is executed to analyze spray characteristics for air-shrouded injector and 4hole 2spray type injector used in a gasoline engine. Since spray parameters including spray penetration and angle, SMD, and atomization characteristics are very important to increase the engine performance, the image processing algorithm for measuring the non-spherical spray diameter is developed. Spray characteristics of the air-shrouded injector(2hole 2spray) and 4hole-2spray injector are analyzed respectively by this digital image processing method. Effective spray characteristics to injectors is derived from this experimentation and obtained the design guide for gasoline injector.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.751-757
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• 2003

With increasing requirements for the less harmful exhaust emissions and the better fuel economy, the conventional injectors in gasoline engines can be replaced by the air shrouded injector in order to provide improved combustion in engine operations. To find out the optimal shape of air shrouded atomizer attached to the conventional injector nozzle, the critical design parameters such as droplet size, fuel and air inlet angles, and injection angles were investigated based on experimental analyses. To explain the characteristics of fuel atomization, these experimental approaches were carried out using a Phase Doppler Particle Analyzer (PDPA) system. The droplet sizes of injected air fuel mixture were obtained by using the beam diffraction phenomenon. In order to improve the atomization effect, the various atomizers were investigated. The Saute. Mean Diameter (SMD) measured at the predetermined locations outside the atomizer represented the performance of fuel atomization. The experimental results show that the design factors and atomization mechanism needed for developing air shrouded injectors. The suggested design parameters in this paper can be a useful reference in the early design stage.

• Journal of ILASS-Korea
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• v.3 no.1
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• pp.10-18
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• 1998

To investigate the in-cylinder phenomena in a SI engine with 3 valves and pent-roof type combustion chamber, flow fields, fuel distributions, and flame propagations were measured in a single c!'tinder visualized engine. Flow fields were visualized by PTV system during the intake and compression process. Fuel distributions were measured by PLIF at the various engine conditions including the cold and hot engine conditions and the effect of air-shrouded injector on the fuel distribution was investigated also. In addition, flame propagation patterns were characterized.

• Journal of ILASS-Korea
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• v.9 no.4
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• pp.17-23
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• 2004

Spray characteristics of a twin-hole air shrouded nonle designed for gasoline injectors was investigated by using laser diffraction particle analyzer (LDPA) and tomography reconstruction- A confined spray chamber which is optically accessible through a pair of glass windows was made to simulate the fuel injection condition in intake manifold of gasoline engine. The measurement was applied to the twin hole injector with and without an air shroud. It demonstrates that for the case with an air shroud, fine atomization is achieved and there exists a large number of fine droplets between the region of the main spray streams, which conforms with the spray visualization. The drop size distribution was investigated as a function of elapse time after fuel injection. The distribution was greatly affected by the measurement position from the injector exit. Also, the spatially resolved spray volume fraction and Sauter Mean Diameter (SMD) from line-of-sight data of the LDPA are tomographically reconstructed by Convolution Fourier transformation under the steady injection condition.

• International Journal of Automotive Technology
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• v.2 no.2
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• pp.63-75
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• 2001

This paper describes the development of THC reduction technologies compliant with SULEV regulations. Technologies embodied by the developmental work include improvement of fuel spray atomization, quick warm-up through coolant control shut of, and acceleration of fuel atomization for the fast rise of cylinder head temp inside the water jacket as well as the improvement of combustion state. The technologies likewise entail reduced HC while operating in lean A/F condition during engine warm-up with the cold lean burn technology, individual cylinder A/F control for improvement of catalytic converting efficiency, after-treatment such as thin-wall catalyst, HC-adsorber and EHC and etc, through vehicle application evaluation in cold start. We carried out an experimental as well as a practical study against SULEV regulations, and the feasibility of adopting these items in vehicle was likewise investigated.