• 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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.302-305
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• 2007

In recent years, many researches on new storage media with high capacity and information are developing. For manufacture of optical storage with high capacity, the injection molding process is generally used. In order to increase the filling ratio of the injection molding structure, the injection molding process required for high injection pressure, packing pressure and temperature control of the mold. However, conventional injection molding process is difficult to increase the filling ratio using injection master with the range of several nanometers and high aspect ratio. In order to improve and increase filling ratio of nano-structure with high aspect ratio, the active temperature control of injection mold was used. Experimental conditions were used injection pressure, time and temperature. Consequently, by using the peltier device into injection mold, we carried out the efficient and active temperature control of mold at low cost.

• 수산해양기술연구
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• 제22권1호
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• pp.41-48
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• 1986

Ifis recommended that the injection rate should be accurate and reliable in the input data of the performance simulation in diesel engine. Matsuoka Sin improved W. Bosch's injection ratio measurement system. Matsuoka Sin reduced length of the test pipe and set the orifice. However, it was not measured accurately to measure the injection ratio due to reflection wave. In the present thesis, the improved measurement system with combination of the conventional W. Bosch type injection ratio measurement system and Matsuoka Sin type corrected W. Bosch type was practically made. The location of orifice and throttle valve was modified and set one more back pressure valve in order to reduce the effect of reflection wave. The results according to injection condition of multi-hole nozzle are following: 1. Measurement error of injection ratio measurement system in this thesis was $\pm$ 1 %, therefore, its reliability was good. 2. The form of injetion ratio is changed from trapezoidal shape to triangle shape with increase of revolution per minute when injection amount is constant. 3. In the case of constant rpm, the initial injection ratio is almost constant regardless of the amount, meanwhile the injection period becomes longer with increase of the amount. 4. The injection pressure of nozzle isn't largely influenced with injection ratio in the case of constant injection amount and rpm, otherwise the initial injection amount is increased by 3-4% when the injection pressure is low. 5. The injection ratio isn't nearly influenced with back pressure.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.28-35
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• 2005

Fuel injection rate of an injector is affected by various injection conditions such as injection duration, fuel temperature, injection pressure, and voltage in LPG liquid injection systems for either a port-fuel-injection(PFI) or a direct injection(DI) in a cylinder. Even fuel injection conditions are changed, the air-fuel ratio should be accurately controlled to educe exhaust emissions. In this study, correction factor for the fuel injection rate of an injector is derived from the density ratio and the pressure difference ratio. A voltage correction factor is researched from injection test results on an LPG liquid injection engine. A compensation method of the fuel injection rate is proposed for a fuel injection control system. The experimental results for the LPG liquid injection system in a SI-engine show that this system works well on experimental range of engine speed and load conditions. And the fuel injection rate is accurately controlled by the proposed compensation method.

• 한국정밀공학회지
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• 제19권7호
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• pp.80-87
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• 2002

Liquefied petroleum gas (LPG) is used in spark ignition (SI) engines. Fuel injection rate of an injector is affected by fuel temperature and pressure in LPG liquid injection systems for either a multi-point-injection (MPI) or a direct injection (DI) engine. Even fuel injection conditions are varied, the air-fuel ratio should be accurately controlled to reduce exhaust emissions. In this study, a correction factor fur the fuel injection rate of an injector is derived from density ratio and pressure difference ratio. A compensation method of injected fuel amount is proposed for a fuel injection control system. The experimental results for the LPG liquid injection system in a SI engine show that this system works well fur a full range of engine speed and load condition, and the air-fuel ratio is accurately controlled by the proposed correction factor.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.24-31
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• 2004

A cylindrical constant volume combustion bomb is used to investigate the combustion characteristics and to analyzer the heat quantity of inhomogeneous charge methane-air mixture. To analyze the heat quantity, some definitions including the CHR ratio, the UHC ratio and the HL ratio are needed and are calculated. It is shown that the effect of stratification is not significant in case of the overall excess air ratio of 1.1, mainly due to the higher heat loss and lower thermal efficiency compared to those of homogeneous condition. In the case of the overall excess air ratio of 1.4, as the initial charge pressure decreases, the CHR ratio has been decreased while the HL ratio has been increased, Generally, as the initial charge pressure increases, the amount of injection mixture has been decreased and has resulted in lower mean velocity and turbulence intensity for injection mixture. Also, the injected mixture is too rich to result in mixing deficiency in combustion chamber. From these results, it could be possible to acquire the improvement of thermal efficiency and the reduction of heat loss simultaneously through the 2-stage injection in CNG direct injection engine.

• 한국분무공학회지
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• 제15권1호
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• pp.17-24
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• 2010

The objective of this work is to analyze the macroscopic behavior of spray and injection characteristics on the DME blended biodiesel at different mixing ratios by using spray visualization and injection rate measurement system. The spray images were analyzed to a spray tip penetration, a spray cone angle and a spray area distribution at various mixing ratio of DME by weight. The influence of different injection pressure and ambient pressure on the fuel spray characteristics are investigated for the various injection parameters. In order to analyze the injection characteristics of test fuels, the fuel injection rate is measured at various blending ratio. The variation of viscosity of the blended fuel by the mixing of DME fuel shows the improved effect of spray developments. Also, it was found that the injection quantities of high blended ratio were larger than that of lower blended fuel. Also, higher blending fuel showed a faster evaporation than that of mixing ratio of test fuel because kinetic viscosity was changed by blending ratio.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.496-501
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• 2003

Computational study is performed to understand the fluidic thrust vectoring control of an axisymmetric nozzle, in which secondary gas injection is made in the divergent section of the nozzle. The nozzle has a design Mach number of 2.0, and the operation pressure ratio is varied to obtain the different flow features in the nozzle flow. The injection flow rate is varied by means of the injection port pressure. Test conditions are in the range of the nozzle pressure ratio from 3.0 to 8.26 and the injection pressure ratio from 0 to 1.0. The present computational results show that, for a given nozzle pressure ratio, an increase of the injection pressure ratio produces increased thrust vector angle, but decreases the thrust efficiency.

• 대한기계학회논문집
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• 제17권10호
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• pp.2590-2600
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• 1993

The present paper describes numerical predictions for the film cooling effectiveness from a row of hole at various injection ratios and injection alngles.Numerical calculations were performed to investigate film cooling effectiveness and the characteristics of flow and temperature distributions in the region near the downstream of injection hole including the region of adverse pressure gradient. The elliptic 3-dimensional governing equations with variable thermal properties were solved by SIMPLE algorithm. The results showed that the presence of adverse pressure gradient in the region near the downstream of injection hole induces large temperature gradient. At injection angle of $35^{\circ}$ the average film cooling effectiveness was increased as increased of injection ratio up to 1.0. At injection angle of $90^{\circ}$ however, the average film cooling effectiveness was decreased from injection ratio larger than 0.4.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.85-88
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• 1995

Recently, the micro mold maching techining technology is developed by means of the mechanical and high energy beam process. It is possible to make the micro structure mold with high aspect ratio by the LIGA technology. This mode is used for mass production of plastic parts by the micro injection molding method. In this study, we intend to research on the basic technology of micro injection molding. As the result, we developed the injection molding technology for small column plastic parts which diameter is 500 .mu. m and 200 .mu. m respectively with wbout aspect ratio 20.