• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.553-558
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• 2001

To find the effective combinations of blowing ratio and injection angle for a straight slot film cooling, film cooling characteristics was investigated using both flow visualization experiment and numerical simulation. Injection angles from $15^{\circ}\;to\;50^{\circ}$ and blowing ratios from 0.2 to 3.0 were selected for the simulation. Comparison between experimental and numerical results shows a good agreement, for the case of the injection angle of $30^{\circ}$ and blowing ratio ranging from 0.55 to 2.0. Film cooling effectiveness was found to be an increasing function of blowing ratio. The effects of injection angle became prominent as the blowing ratio increases. An interesting phenomenon was found for the injection angle of $15^{\circ}$ : the lowest film cooling effectiveness for the blowing ratio smaller than 1.0, but the highest film cooling effectiveness for the blowing ratio greater than 2.0 within wide range of downstream region. There exist optimum injection angles corresponding to maximum film cooling effectiveness : injection angle of $25^{\circ}$ for the blowing ratio from 0.2 to 2.0, and injection angle of $15^{\circ}$ for the blowing ratio of 3.0. Present study provides a design combination among film cooling effectiveness, blowing ratio, and injection angle.

• 대한기계학회논문집B
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• 제25권7호
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• pp.933-943
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• 2001

Using a semi-circled blunt body model, the geometrical effects of injection hole on the turbine blade leading edge film cooling are investigated. The film cooling characteristics of two shaped holes (laterally- and streamwise-diffused holes) and three cylindrical holes with different lateral injection angles, 30°, 45°, 60°, respectively, are compared with those of cylindrical hole with no lateral injection angle experimentally and numerically. Kidney vortices, which decrease the adiabatic film cooling effectiveness, appear on downstream of the cylindrical hole with no lateral injection angle. At downstream of the two shaped holes have better film cooling characteristics than the cylindrical one. Instead of kidney vortices, single vortex appears on downstream of injection holes with lateral injection angle. The adiabatic film cooling effectiveness is symmetrically distributed along the lateral direction downstream of the cylindrical hole with no lateral injection angle. But, at downstream of the cylindrical holes with lateral injection angle, the distribution of adiabatic film cooling effectiveness in the lateral direction shows asymmetric nature and high adiabatic film cooling effectiveness regions are more widely distributed than those of the cylindrical hole with no lateral injection angle. As the blowing ratio increases, also, the effects of hole shapes and injection angles increase.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2454-2459
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• 2008

The objective of this paper is to find out the most effective injection angle for the purpose of deicing through SC/Tetra, a commonly used CFD software. Nowadays, vehicles are developed giving priority to an improved interior which emphasizes a pleasant environment and thermal comfort without decreasing the basic performance. Clear visibility is one of the most important phenomenon. The primary factors which affect the efficiency of deicing are 3D geometry of Defrost Nozzle, the inlet velocity and temperature of the flow and the injection angle. However in this paper, all these parameters are optimized by changing the injection angle. A wide range of injection angle from 5 degree to 50 degree have been considered for analysis. A very good defrosting performance has been achieved with 45 degree injection angle which can satisfy the condition of NHTSA.

• 한국분무공학회지
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• 제11권3호
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• pp.161-167
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• 2006

As the exhaustion of petroleum resources and air pollution problems are getting serious recently, there are growing interests in premixed diesel engines which have the potential of achieving a more homogeneous mixture near TDC compared to conventional diesel engines. Early studies have shown that the fuel injection frequency and spray angle affected the mixture formation and combustion in a HCCI(Homogeneous Charge Compression Ignition) engine. Therefore, the purpose of this study is to investigate the relationship between combustion and mixture formations by injection timing and frequency using a narrow angle injector, NADI (Narrow Angle Direct Injection). In this study, we found that the fuel injection timing and injection frequency affect the mixture formations and then affect combustion in the HCCI engine.

• 한국자동차공학회논문집
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• 제23권2호
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• pp.221-229
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• 2015

The PFI dual injection engine using one injector per an intake port was developed for solving the DISI engine cost problem. Excellent fuel atomization and targeting of the PFI dual injection engine made enhancement on the fuel efficiency and engine power. In order to develop a PFI dual injection engine, characteristics of the in-cylinder flow and fuel behavior with respect to fuel injection angle and cone angle of the PFI dual injection engine was investigated. Numerical calculation was conducted to analyze 3D unsteady in-cylinder flow and fuel behavior using STAR-CD. The engine operating condition was 2,000rpm at WOT. As a result, the amount of intake air, evaporated fuel and fuel film according to injection angle and cone angle were presented. The results were influenced by interaction between injected fuel and intake port wall.

• 한국자동차공학회논문집
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• 제14권4호
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• pp.20-25
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• 2006

Recently, there has been an interest in premixed diesel engines as it has the potential of achieving a more homogeneous and leaner mixture close to TDC compared to conventional diesel engines. Early studies are shown that in a HCCI(Homogeneous Charge Compression Ignition) engine, the fuel injection timing and injection angle affects the mixture formations. Thus the purpose of this study was to investigate relationship of combustion and mixture formations according to injection timing and injection angle in a common rail direct injection type HCCI engine using a early injection method called the PCCI(Premixed Charge Compression Ignition). From this study, we found that the fuel. injection timing and injection angle affect the mixture formations and in turn affects combustion in the PCCI engine.

• 한국분무공학회지
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• 제16권4호
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• pp.201-209
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• 2011

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.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.182-190
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• 1998

Behaviour of ultra-high pressure diesel spray in a constant-volume pressure chamber was studied with injection pressure ranging from 20 to 160㎫. Sprays were observed by the right angle scattering method. As a result, the spray tip penetration is first proportional to a time, and after that, it is proportional to 0.52 of the time during at the time of injection pressure and back pressure increase. An empirical correlation was made for the parameters of injection pressure, air-fuel density ratio, spray tip distance, spray angle, jet angle of spray and max. spray width.

• 한국분무공학회지
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• 제26권4호
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• pp.197-203
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• 2021

In gasoline direct injection injectors, cavitation can be generated inside the hole because of their high injection pressure. In this paper, the effects of cavitation development in injector were investigated depending on the various hole drilling angles were investigated by a numerical method. In order to verify the internal flow model, injection rate and injection quantity of individual holes were measured. The BOSCH long tube method was used to measure the injection rate. As a result, even if the hole diameters were the same, the discharge coefficient differed by up to 10% depending on the hole angle. Moreover, if the hole drilling angle became greater than 30°, the area coefficient and the discharge coefficient decreased as the nozzle outlet was blocked due to cavitation.

• 한국분무공학회지
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• 제29권1호
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• pp.32-37
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• 2024

Macroscopic visualization of non-evaporating sprays was experimentally conducted to investigate spray tip penetration and spray angle under low-density conditions, corresponding to an early injection strategy. Furthermore, injectors with varying injection angles (146° and 70°) and numbers of holes (8 and 14) were employed to examine the impact of injector configuration. Compared to the baseline injector, 8H146, which has 8 holes and a 146° injection angle, the spray tip penetration of the 8H70 injector was found to be longer. This can be attributed to higher momentum due to a smooth flow field between the sac volume and the nozzle inlet, which is located closer to the injector tip centerline. The increase in velocity led to intense turbulence generation, resulting in a wider spray angle. Conversely, the spray tip penetration of the 14H70 injector was shorter than that of the 8H70 injector. The competition between increased velocity and decreased nozzle diameter influenced the spray tip penetration for the 14H70 injector; the increase in momentum, previously observed for the 8H70 injector, contributed to an increase in spray tip penetration, but a decrease in nozzle diameter could lead to a reduction in spray tip penetration. The spray angle for the 14H70 injector was similar to that of the 8H146 injector. Moreover, injection rate measurements revealed that the slope for a narrow injection angle (70°) was steeper than that for a wider injection angle during the injection event.