• Journal of ILASS-Korea
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• v.4 no.4
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• pp.9-16
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• 1999

Spray angle, a parameter which is most commonly used to evaluate. spray distribution, is important because it affects the axial and radial distribution of the fuel. Spray angles were measured and compared for the pintle-type gasoline fuel injector with n-heptane as a test fuel with the three different measuring techniques, i.e. digital image processing, shadowgraphy and spray patternator, respectively. Fuel was injected with the injection pressures of 0.2-0.35MPa into the room temperature and atmospheric pressure environment. In digital image processing method, the transmittance level greatly influences the spray angle with the axial distance from the injector. From the experimental results by the shadowgraphy technique, it is obvious that the spray angle vary during the injection period. The results of spray angle from the spray patternator show that there exist the different spray angles in the different areas. The spray angles increase with the increase in the injection pressure for the three measurement techniques considered in this study. The spray angle is widely different, especially in the near region from the injector, according to the measurement techniques used in this experimental work.

• Journal of ILASS-Korea
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• v.29 no.2
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• pp.83-90
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• 2024

Understanding the fundamental characteristics of supersonic hydrogen jets is important for the optimization of combustion in hydrogen engines. Previous studies have used helium as a surrogate gas to characterize the hydrogen jet characteristics due to potential explosion risks of hydrogen. It was based on the similarity of hydrogen and helium jet structures in supersonic conditions that has been confirmed using hole-type injectors and large-cone-angle pintle-type injectors. However, the validity of using helium as a surrogate gas has not been examined for recent small-cone-angle pintle-type injectors applied to direct-injection hydrogen engines, which form a supersonic hollow cone near the nozzle and experience the jet collapse downstream. Differences in the physical properties of hydrogen and helium could alter the jet development characteristics that need to be investigated and understood. This study compares supersonic jet structures of hydrogen and helium injected by a small-cone-angle (50°) pintle-type hydrogen injector and discusses their differences and related mechanisms. Jet penetration length and dispersion angle are measured using the Schlieren imaging method under engine-like injection conditions. As a result, the penetration length of hydrogen and helium jets showed a slight difference of less than 5%, and the dispersion angle showed a maximum of 10% difference according to the injection condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.54-61
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• 2001

It is reported that during the cold starting, especially in gasoline engine, the engine response and the effect of HC emission can be improved by prompting atomization and reducing the quantity of fuel adhered to the range of injector tip, inlet port, and inlet valve. The purposes of this study are to promote atomization of fuel before air-fuel mixture in the inlet port. In order to achieve its goal, the glow plug is to evaluate the feasibility of for the early fuel evaporator and the spray behavior characteristics of gasoline, injected on the surface of glow plug with room temperature(2$0^{\circ}C$) and high temperature(25$0^{\circ}C$) is to examine. Particle motion analysis system(PMAS) was used to measure the SMD and the dropsize distribution of impinging spray and free spray. The results of this experiment, evaporation rate of impinging spray was higher than that of free spray, and the higher evaporation rate win, the smaller peak dropsize was. Especially, during early spray SMD of impinging spray was still smaller than that of fee spray.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.17-23
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• 1998

A simplified experiment was performed to figure out the atomization characteristics of highly viscous liquid of rice-bran oil by applying ultrasonic energy to improve the atomization of spray droplets. A spray system, an ultrasonic system, and three kinds of pintle-type nozzles(pin-edge angle: 5 , 10 , 15 ) were manufactured. To investigate the effects of ultrasonic energy on the atomization of a highly viscous liquid, a phase doppler particle analyzer was used for the measurement and calculation of spray droplets data. Nozzle opening pressures were chosen of 3 levels, i.e, 10, 13, 16 MPa. As a result, it could be concluded that the ultrasonic energy was effective to improve the spray atomization when applied to the fuel by means of 3 different nozzles because of the effects of the liquid fuel cavitation and relaxation between molecules caused by ultrasonic energy. The improvement rate of the spray atomization by the ultrasonic spray atomization by the ultrasonic spray compared with the conventional spray was about 10% increase in the case of pintle type nozzles. With the increase of pin-edge angles the distribution lines by nozzle opening pressures are declined for both conventional and ultrasonic sprays. This means that the increase of the pin-edge angle improves the atomization of sprays.