http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
개별검색 DB통합검색이 안되는 DB는 DB아이콘을 클릭하여 이용하실 수 있습니다.
통계정보 및 조사
예술 / 패션
<해외전자자료 이용권한 안내>
- 이용 대상 : RISS의 모든 해외전자자료는 교수, 강사, 대학(원)생, 연구원, 대학직원에 한하여(로그인 필수) 이용 가능
- 구독대학 소속 이용자: RISS 해외전자자료 통합검색 및 등록된 대학IP 대역 내에서 24시간 무료 이용
- 미구독대학 소속 이용자: RISS 해외전자자료 통합검색을 통한 오후 4시~익일 오전 9시 무료 이용
※ 단, EBSCO ASC/BSC(오후 5시~익일 오전 9시 무료 이용)
Of the macroscopic spray characteristics of non-reacting diesel fuel sprays, the spray angle reflects directly the atomization and air entrainment processes downstream the nozzle. In addition, spray angle is important because it will be closely related to the spray penetration. The existing definitions for the measurement of spray angle as well as the correlations for the prediction of spray angle are, therefore, summarized and reviewed. The existing definition of spray angle can be classified into four groups: distance based on orifice diameter, distance based on spray tip penetration, definition based on surface wave, and definition based on atomization. It is strongly required to specify the definition and measurement method when the data for spray angle is reported. The existing correlations for spray angle can be classified into two groups: theoretical and empirical correlations. The study on the evaluation of the existing correlations fer spray angle is required.
Macroscopic visualization of non-evaporating spray was carried out experimentally to investigate spray tip penetration and spray angle in term of low density condition corresponding to the early injection strategy. In addition, injectors with different injection angle, which refer to spray included angle, (146° and 70°) and number of hole (8 and 14) were applied to study the effect of the injector configuration. Compared with 8H146, which is regarded as baseline injector with 8 holes and 146° injection angle, spray tip penetration for 8H70 injector showed longer that for 8H146. It is attributed higher momentum and velocity due to smooth flow field in sac volume and nozzle, which was located closer to injector tip centerline. Intense turbulence generation due to the increase in velocity resulted in wide spray angle. On the other hand, spray tip penetration for 14H70 injector was smaller than that for 8H70 injector. Competition between increase in velocity and decrease in nozzle diameter bring about spray tip penetration for 14H70 injector, i.e., increase in momentum, which previously showed for 8H70 injector, contributed to the increase in spray tip penetration, but decrease in nozzle diameter could result in the decrease in the spray tip penetration. Spray angle for 14H70 injector was similar to that for 8H146 injector. Moreover, injection rate measurement reveals that slope for narrow injection angle (70°) was steeper than that for wide injection angle during injection event. Based on the experimental results, assessment of spray tip penetration model was carried to investigate the effect of injector configuration under low ambient gas density condition. Because previous model of spray tip penetration has no information on the injection angle, developed formula in this paper can apply the spray evolution from injector with same nozzle diameter and different injection angle. The formula showed good agreement with experimental results except initial stage of spray evolution.
The swirl spray for direct injection gasoline engines was controlled using the tapered nozzles to fulfill the requirement of various combustion systems and the control mechanism causing the spray alterations were investigated. This study focused on how the correlation between taper angle, inclined angle of tapered nozzle, and flow angle affects the swirl spray shape. The macroscopic spray images were captured and velocity and droplet size distribution of tapered nozzle swirl spray were measured to understand the spray alterations at different taper angles. The result showed that fuel did not pass some area of nozzle exit and U or V shape spray was generated when the taper angle was higher than 90o minus flow angle. The velocity and fuel distribution of swirl spray were more asymmetrical and the spray robustness was enhanced when the taper angle was increased. The opened swirl spray, U or V shape spray generated when the taper angle is more than 90o minus flow angle, showed the possibility for the application of spray-guided combustion system as a result of enhanced spray momentum and reduced static air pressure drop inside the spray compared with the conventional swirl spray.
Hydrotreated biodiesel (HBD) would be one of the promising alternative fuels instead of current biodiesel. In this study, Investigation of spray characteristics in terms of spray penetration and spray angle were conducted experimentally including calculated SMDs as well. The ambient pressures of 1, 3, and 5 MPa and injection pressures of 30, 80, and 130 MPa were introduced and the fuels employed were petro-diesel, and 2, 10, 20, 30, and 50 % for hydrotreated biodiesel, respectively. 6 holes of Bosch injector was used for this study with 156 degree of injection angle and 0.120 mm of nozzle diameter. In this study, spray tip penetrations were measured and analyzed between 0.0 ms and 3.0 ms after start of injection. Pictures were taken at every 0.1 ms of time frames. It was difficult to measure spray angles because of low resolution. Thus, spray angles were measured after 0.2 ms of injection. Test result shows that the distinct differences in penetration length among fuels were shown regardless of ambient pressure in the low injection pressure like 30 MPa. At the same injection pressure such as 130 MPa, the spray penetration length at ambient pressure of 1Mpa shows three times higher than that of 5Mpa. Spray tip penetrations were mostly affected by the injection pressure and ambient pressure. Thus, there were little significant differences of spray tip penetrations among test fuels at the same conditions. Nevertheless, the more HBD blended diesel shows relatively shorter penetration length because of lower density than that of petro-diesel. On the contrary, the more biodiesel blended fuel shows the longer penetration length because of higher density than that of petro-diesel. Relatively larger spray angles were observed to the more HBD blended diesel than petro-diesel at the same time frame after injection. The more biodiesel blended diesel shows smaller spray angle as opposed to HBD, because of the difference of their density, kinetic viscosity and surface tension. Spray angle increases appreciably with increase in nozzle diameter, and diminishes with increase in ambient density, liquid viscosity, and injection pressure of liquid. Spray angle decreases with increase in viscosity. Surface tension had no appreciable effect on spray angle. Spray angle widens slightly with increase in density. SMD correlations among surface tensions, densities and viscosities of petro-diesel and HBD blended diesels were calculated by means of two typical numerical equations, which is the regression model developed from the experimental data acquired using Malvern Particle Size Analyzer. The results on SMD can be seen that viscosity has more positive effects than density. Therefore, the more HBD blended fuels were shown the slightly larger SMDs than petro-diesel, because of larger viscosity of HBD than that of petro-diesel. Consequently, this study has found that HBD has a little bit merits and demerits of macro- and microspray patterns compared to petro-diesel.
Optimum engine performance is obtained when the spray characteristics is well matched to the geometry of a combustion chamber. Among many parameters governing the combustion performance in internal combustion engine, fuel supply characteristics and atomization are important performance factors. Therefore, spray characteristics of high pressure multi-hole injector has been studied experimentally. An experimental test system has been made to operate high pressure injection system and to visualize spray behavior. Spray visualization has been performed to analyze spray formation, spray cone angle, bent angle and penetration length. Spray interaction with piston has been analyzed with various injector installation angle, injection pressure and ambient pressure. Test results show that penetration length is greatly influenced by the injection pressure. Penetration length is decreased as ambient pressure increased. Spray cone angle is increased as injection pressure and ambient pressure increased. However, bent angle is not influenced by the change of injection pressure and ambient pressure. Spray cone angle distribution map is plotted using the experimental data. Fuel movement around the spark-plug has been enforced as increasing injector installation angle.
Spray angle is one of the key spray macro parameters which reflect fuel atomization characteristics and fuel and air entrainment quality directly; it then could affect the combustion efficiency and emission formation in cylinder. As the spray characteristics are widely investigated, there are already some kinds of definition and calculation methods for spray angle. Although all these definitions reflect the spray angle trends correspondingly, the difference between these definitions and calculation results was seldom studied. This paper focuses on the comparison and analysis the spray angle results based on the different calculation criterions, and the trend of these key points versus time at various calculation criterions which determine spray angle.
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.
The beneficial aspects of applying emulsion fuels to combustion systems may be due to the changes of fuel properties which lead to the enhanced atomization characteristics. The spray characteristics of water/oil emulsified fuel injected from the pressure-swirl(simplex) atomizer using for oil burner were investigated. Four different water contents from 10 to 40 % by volume at 10% increment were prepared by mixing with the different contents of surfactants. Total amount of surfactant used was varied from 1 to 3 % by volume. This study demonstrates the influence of water and surfactant contents of emulsified fuel, injection pressure on the spray characteristics, i.e. Sauter mean diameter(SMD) and spray angle. The drop size distribution of the emulsified fuel spray was measured with a Malvem particle sizer. In order to measure the spray angle, the digital image processing was employed by capturing multiple images of the spray with 3-CCD digital video camera. It was evident that the addition of water and surfactant changes fuel properties which are the key parameters influencing the atomization of the spray. The increase in surfactant content results in the decrease of SMD and the increase in spray angle. The droplets decease with increase in injection pressure, but the influence of injection pressure in this experimental condition was less important than expected. The more viscous fuel with the increase of water content exhibits the larger droplets in the centerline of the spray, and the less viscous fuel in the outer edges of the spray. The increase in axial position from the nozzle causes the spray angle to decrease. The spray angle decreases with increase in water content. This is due to increase in viscosity with increase in water content.
The spray characteristics of swirl spray at different taper angles are investigated and then a taper angle, generating an opened hollow cone spray, is chosen to create the robust swirl spray at various surrounding conditions. The tapered nozzle altered the symmetrical distribution of fuel and velocity to asymmetrical state. The larger portion of fuel was positioned in some area with higher injection velocity, and the smaller portion of fuel was located in another area with lower injection velocity. When the taper angle was decreased, the fuel velocity to a certain direction was getting increased and spray images showed more asymmetrical shape. By cutting the nozzle to have a tapered nozzle with an angle less than the flow angle, opened hollow cone spray was formed because some part of fuel impinges to the cut area. This shape assists in equalizing the pressure difference between the centerline and outer part of spray envelop. The results showed that there is a potential from a tapered nozzle spray to be independent of the various surrounding conditions without much sacrifice of the atomization quality when the taper angle is less than the flow angle.
The present study has been conducted to quantify the spray angle which is a common parameter for sprinkler spray analysis. Imaging processing technique based on the laser visualization is compared with measurement of spray patterns by momentum signal using the piezo-electric sensor. A DPSS laser with 100 mW power and 532 nm wave length was utilized for the visualization of sprinkler spray and the outer spray angle was measured to 145º for the reference operating condition of sprinkler. A spray patternator using momentum signal of spray droplets was made with the piezoelectric sensor array and the diameter of the individual sensor is 20 mm. The measured spray angle using the spray patternator with piezo-electric sensor is ranged about 140°~150° and shows good agreement with that of the laser visualization technique. This study can contribute to understanding the spray characteristics of sprinkler head and utilizing the fire safety analysis with sprinkler activation.