• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.36-46
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• 2000

The performance improvement and emission reduction in a turbocharged D.I. diesel engine was studied experimentally in this paper. The system of intake port, fuel injection and turbochager are very important factors which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. Through these experiments it can be expected to meet performance and emission by optimizing the main parameters; the swirl ratio of intake port, fuel injection system and turbocharger. The swirl ratio of intake port was modified by hand-working and measured by impulse swirl meter. Through this steady flow test, we knew that the increase of swirl ratio is decreasing the mean flow coefficient, whereas the gulf factor is increasing. And the optimum results of engine performance and emission are as follows; the swirl ratio is 2.43, injection timing is BTDC 13。 CA, compression ratio is 16, combustion bowl is re-entrant 5$^{\circ}$, nozzle hole diameter is $\Phi$0.28＊6, turbocharger is GT40 model which are compressor A/R 0.58 AND turbine A/R 1.19.

• Journal of ILASS-Korea
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• v.2 no.2
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• pp.8-15
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• 1997

Combustion chamber systems using spray impinged on walls have been studied for improving combustion characteristics in high speed direct injection diesel engines. The fuel spray injected in a small combustion chamber may be easily impinged and deposited on the wall. The fuel deposit has been considered as the cause for unburned emission due to difficulty of fuel-air mixing. In this paper w-shaped combustion chamber which has four raised pips on the side wall is introduced and discussed by comparing with conventional chamber with no pips. The computer code employing new spray-wall interaction model in general non-orthogonal grids is used in here. The model is applied into the new chamber shape with raised pips. In this chamber system four-hole nozzle is used, and the sprays injected from the each hole impact on lands raised from the chamber wall surface. After impacting, the sprays break up into much smaller drops and distribute over all the chamber space, instead of distributing just near the wall surface in conventional omega-shape. The results showed the potential of the w-shaped chamber employing pips for dispersing droplets so as tn avoid the fuel deposit regions.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.1
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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.

• Journal of ILASS-Korea
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• v.29 no.1
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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.

• Journal of Energy Engineering
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• v.11 no.2
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• pp.90-98
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• 2002

The effects of swirl and combustion parameters on the performance and emission in a turbo-charged D.I. diesel engine of the displacement 9.4L were studied experimentally in this paper. Generally the swirl in the combustion process of diesel engine promotes mixing of the injection fuel and the intake air. It is a major factor to improve the engine performance because the fuel consumption and NO$_{x}$ is trade-off according to the high temperature and high pressure of combustion gas in a turbocharged D.I. diesel engine, it's necessary to thinking over the intake and exhaust system, the design of combustion bowl and so on. In order to choose a turbocharger of appropriate capacity. As a result of steady flow test, when the swirl ratio is increased, the mean flow coefficient is decreased, whereas the gulf factor is increased. Also, through engine test its can be expected to meet performance and emissions by optimizing the main parameter's; the swirl ratio is 2.43, injection timing is BTDC 13$^{\circ}$ CA, compression ratio is 16, combustion bowl is re-entrant 5$^{\circ}$, nozzle hole diameter is $\Phi$0.28*6, turbocharger is GT40 model which are compressor A/R 0.58 and turbine A/R 1.19.

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.4
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• pp.63-74
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• 1989

It is well-known that the fuel injection system if a diesel engine has taken a more important place in understanding of diesel combustion process with combustion chamber. But a diesel fuel injection system has an assembly of many complex and intricate problems such as the desired rate of injection, secondary injection and injection pump etc., in addition to the atomization for ignition and combustion, the penetration and diestribution for proper utilization of air. The analysis is carried out by simplifing and modeling the injection phenomena and dividing into three parts comprising of fuel injection pump, high pressure pipe and fuel injection nozzle. The purpose of this paper is to describe an analytical simulation of the injection system and to speed up the work of developing injection systems for new engines. The effects of important injection parameters as predicted by the present model are found to be in good agreement with experiment. It can be seen that there is an optimal pipe diameter for maximum quantity injected.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.764-767
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• 2003

The characteristics of diesel spray have much effect on the engine performances such as power. fuel consumption rate and emissions. Therefore, the measurement of fuel spray characteristics is very important for the improvement of heat engine. The factors which control diesel spray characteristics are injection pressure, ambient temperature and density etc. Spray behaviors are visualized by using the high speed video camera and spray angle, spray penetration are measured. Experimental equations of spray penetration and spray angle were derived by using the experimental results. 1) Ambient temperature and density influence on the characteristics of diesel spray. 2) Experimental equation of spray penetration is expressed as follows 0＜t＜ $t_{b}$ ; $S_1$=11.628$\Delta$ $P^{0.485}$ $\rho$$_{a}$ $^{-0.478}$ $t^{1.337}$, $t_{b}$ ＜t; $S_2$=7.457$\Delta$ $P^{0.523}$ $\rho$$_{a}$ $^{-0.382}$ $t^{0.548}$ 3) Experimental equation of spray Angie is expressed as follows $T_{a}$ =293K; Tan($\theta$/2)=059($\rho$$_{a}$ / $\rho$$_{f}$ )$^{0.437}$, $T_{a}$ =473K; Tan($\theta$/2)=0588($\rho$$_{a}$ / $\rho$$_{f}$ )$^{0.404}$_{f}$ )$^{0.404}$

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.1
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• pp.105-113
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• 2009

The performance of a direct-injection type diesel engine often depends on the strength of swirl or squish, shape of combustion chamber, the number of nozzle holes, etc. This is of course because the combustion in the cylinder was affected by the mixture formation process. In this paper, combustion process of biodiesel fuel was studied by employing the piston which has several grooves with inclined plane on the piston crown to generate swirl during the compression stroke in the cylinder in order to improve the atomization of high viscosity fuel such as biodiesel fuel and toroidal type piston generally used in high speed diesel engine. To take a photograph of flame, single cylinder, four stroke diesel engine was remodeled into two stroke visible engine and high speed video camera was used. The results obtained are summarized as follows; (1) In the case of toroidal piston, when biodiesel fuel was supplied to plunger type injection system which has very low injection pressure as compared with common-rail injection system, the flame propagation speed was slowed and the maximum combustion pressure became lower. These phenomena became further aggravated as the fuel viscosity gets higher. (2) In the case of swirl groove piston, early stage of combustion such as rapid ignition timing and flame propagation was activated by intensifying the air flow in the cylinder. (3) Combustion process of biodiesel fuel was improved by the reason mentioned in paragraph (2) above. Consequently, the swirl grooves would also function to improve the combustion of high viscosity fuel.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1489-1495
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• 2013

High-pressure flows are ubiquitous in many industrial fields. A representative application is fuel injection using a common-rail control system in diesel engines, where the injection pressure in the injector exceeds 1000 bar. In high-speed injection, the fluid injected through the nozzle undergoes breakup owing to the interaction with the ambient gas. The breakup process influences mixture formation, which in turn influences combustion in diesel engines. Therefore, it is very important to analyze the breakup process of fuel spray. The Reitz and Diwakar model and cascade atomization and breakup (CAB) model were used in this study as sub-models for the numerical analysis of the breakup process of fuel spray. This study aims to precisely analyze the breakup process of spray and to investigate the breakup frequency of the injected fuel. Consequently, it proposes a suitable sub-model for analyzing the breakup process of a diesel spray by using CFX, a commercial CFD program.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.91-99
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• 2014

The common-rail injectors are the most critical component of the CRDI diesel engines that dominantly affect engine performances through high pressure injection with exact control. Thus, from now on the advanced combustion technologies for common-rail diesel injection engine require high performance fuel injectors. Accordingly, the previous studies on the numerical and experimental analysis of the diesel injector have focused on a optimum geometry to induce proper injection rate. In this study, computational predictions of performance of the diesel injector have been performed to evaluate internal flow characteristics for various needle lift and the spray pattern at the nozzle exit. To our knowledge, three-dimensional computational fluid dynamics (CFD) model of the internal flow passage of an entire injector duct including injection and return routes has never been studied. In this study, major design parameters concerning internal routes in the injector are optimized by using a CFD analysis and Response Surface Method (RSM). The computational prediction of the internal flow characteristics of the common-rail diesel injector was carried out by using STAR-CCM+7.06 code. In this work, computations were carried out under the assumption that the internal flow passage is a steady-state condition at the maximum needle lift. The design parameters are optimized by using the L16 orthogonal array and polynomial regression, local-approximation characteristics of RSM. Meanwhile, the optimum values are confirmed to be valid in 95% confidence and 5% significance level through analysis of variance (ANOVA). In addition, optimal design and prototype design were confirmed by calculating the injection quantities, resulting in the improvement of the injection performance by more than 54%.