• 한국자동차공학회논문집
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• 제5권1호
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• pp.146-153
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• 1997

An experiment was conducted to figure out the atomization characteristics of a highly viscous biodiesel fuel with rice-barn oil applying and ultrasonic energy into it. A spray simulator for the droplet atomization, an ultrasonic system, and six different nozzles(3 pintle-type nozzles and 3 single hole-type nozzles) were made. To investigate effects of ultrasonic energy in a highly viscous liquid fuel, an immersion liquid method was used as a measurement method on droplet size distributions. It was found that the ultrasonic energy was effective for the atomization improvement of the rice-bran oil as a highly viscous biodiesel fuel and the factor나 such as the nozzle opening pressure, pin-edge angles, hole diameters, and collection distances affected the atomization of spray droplets.

• 에너지공학
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• 제13권4호
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• pp.235-241
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• 2004

본 연구는 초음파 개질 바이오 디젤유의 점도와 표면장력에 대한 연료의 물리적 특성, 분무 미립화 특성에 관한 심층적이고 체계적인 연구에 중점을 두었다. 이를 규명하기 위하여 초음파 재질 연료와 개질 되지 않은 연료의 상대 비교 분석을 통한 연료특성과 연료분사펌프의 회전수 및 노즐선단 거리변화에 의한 입경측정의 상관성을 정립하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제13권4호
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• pp.63-74
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• 1989

디젤기관의 연료분사계는 연소실과 함께 디젤기관의 성능에 가장 큰 영향을 미치는 요소의 하나로 이에 대한 이해는 디젤연소 규명에 있어서 매우 중요하다. 그러나 이분사계는 발화 및 완전연소에 필요한 무화, 공기의 이용율을 증가시키는 관통성 및 분포성등의 요건뿐만 아니라 요구되는 분사율, 2차분사 그리고 분사펌프와의 결합등의 많은 문제와 연관되어 있다. 따라서 본 연구에서는 이와 같이 복잡한 디젤기관의 연료분사계를 단순화시켜서 펌프측, 노즐측 및 분사파이프측의 세부분으로 나누어 모델링하여 해석함으로써 새로운 연료분사계의 개발을 위한 기초연구자료를 구하는 것을 목적으로 하였다. 분사파이프내의 압력과 분사계의 실험을 통하여 본 모델의 타당성을 검토하였으며 각 분사계에 있어서 분사량을 최대로 하는 분사파이프직경이 존재함을 확인할 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.645-652
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• 2010

본 연구의 목적은 다양한 분위기 압력 하에서 커먼레일 디젤인젝터를 통해 분사되는 비증발 디젤 분무특성에 관한 연구이다. 디젤분무의 거시적 특성으로 분무관통거리와 분무각을 음영사진과 이미지프로세싱으로 연구하였다. 수치해석은 상용 CFD프로그램인 AVL-FIRE를 사용하였다. 분열모델은 WAVE모델을 사용하였으며 표준 $k-{\varepsilon}$난류모델을 적용하였다. 분무각과 Zeuch법을 적용한 연료 분사율을 수치해석의 입력값으로 사용하였다. 분무관통거리를 실험값과 비교하여 좋은 결과를 얻었고 수치해석을 통하여 노즐팁 하류방향으로 분무의 각 구간별 액적입경분포를 알아보았다.

• 수산해양기술연구
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• 제32권3호
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• pp.316-320
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• 1996

터빈 노즐 면적을 최적화함과 동시에 동기화 시킴으로서 기관의 싸이클 특성의 변화를 시도하였다. 그 결과 동력 추출을 위한 가스 유동이 제한을 받게 되고 최종의 팽창비 $\delta$에 의하여 싸이클의 변화가 이루어졌으며 동력의 이득은 싸이클 효율이 증가됨으로써 성취되었다.

• 에너지공학
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• 제11권2호
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• pp.90-98
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• 2002

본 연구는 선회유동과 연소인자가 9.4L인 터보과급 디젤엔진의 성능과 배기가스특성에 미치는 영향을 실험적으로 고찰하였다. 일반적으로 디젤엔진의 연소과정에서 선회유동은 분사되고 있는 연료와 흡칩공기의 혼합을 촉진시켜 줌으로써 엔진성능을 향상시키는데 매우 중요한 인자가 된다. 특히 터보과급 디젤엔진에서는 실린더내의 고온.고압가스로 인하여 연비와 NO$_{x}$ 농도는 서로 상반관계를 가지므로 적절한 용량의 과급기선정으로 흡.배기시스템, 분사시스템 및 연소실의 설계 등을 고려할 필요가 있다. 본 연구의 결과로서, 정상유동실험을 통하여 선회비가 증가함으로써 평균유량계수가 감소하고, 반면에 걸프 펙터가 증가함을 알 수 있었다. 또한 엔진실험을 통하여 흡기포트의 선회비 2.43, 분사시기 BTDC 13$^{\circ}$ CA, 압축비 16, 리앤트란트 5$^{\circ}$형 연소실, 노즐분공경 $\Phi$0.28*6 및 과급기 GT40(압축기 A/R 0.58, 터빈 A/R 1.19)의 적용인자가 최적의 성능 및 배기가스를 만족시킬 수 있었다.

• 한국분무공학회지
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• 제4권1호
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• pp.45-54
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• 1999

The spray characteristics of a direct injection multi-hole diesel nozzle having the 2-spring nozzle holder were investigated by using the image processing system and a PDPA(phase Bowler particle analyzer) system. The spray tip penetration, the spray angle, and the droplet diameter and velocity with the variation of the pump speed, injection quantity were measured. From, the experiments, we know that there are small droplets which are not to be detected with spray image around the leading edge of the spray. In order to represent the mean characteristics of the intermittent spray very well, it is very important to set the time windows accurately. From the measurements along the axis of the spray, close to the nozzle, the initially injected droplets are overtaken by droplets that follow them. And also there are the maximum axial mean velocity and SMD at the following part of the leading edge of the spray.

• 한국자동차공학회논문집
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• 제5권4호
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• pp.160-170
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• 1997

The objective of this study is to investigate the atomization characteristics and the performance characteristics of a C. I. engine by using the changes of the injection nozzle type and the ultrasonic-energy-added system. In order to evaluate the effect of ultrasonic energy and of change of injection nozzle type in the performance characte- ristics of a diesel engine, measurements of droplet size of diesel fuel were carried out by using Malvern system. In all types of injection nozzles, SMD of the ultrasonic- energy -added diesel fuel was smaller than that of the conventional diesel fuel and the more injection pressure increased, the more SMD decreased. There was a small increase in SMD with the distance from injection nozzle under all conditions of the injection nozzle types. The minimum SMD was found in the injection nozzle of B type. In the diesel engine test, there were three results about the engine performance. Compared with the injection nozzle of A type, B type had excellent effects in the engine performance. The most excellent effects about the engine performance were obtained in the case of ultrasonic-energy-added diesel fuel. In addition, the torque diagram in the case of ultrasonic-energy-added diesel fuel was more stable and periodical than others.

• Journal of Advanced Marine Engineering and Technology
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• 제28권7호
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• pp.1123-1130
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• 2004

Numerical simulations have been carried out to investigate the effect of nozzle hole geometry on the combustion characteristics of the large diesel engine. 6S90MC-C. Spray and combustion phenomena were examined numerically using FIRE code. Wane breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation processes. Predictions on the cylinder peak pressure and NOx emission were first verified with the experimental data to confirm the reliability of numerical calculations. The comparison results showed good agreements within the range of 0.64% and 4.6% respectively. Finally, the effects of fuel spray angle and diameter on the engine performance were investigated numerically to find the optimum nozzle hole geometry considering fuel consumption, NOx emission and heat flux of the combustion chamber wall. It was concluded that the combustion gas recirculation in cylinder by changing fuel injection direction is an effective method to reduce NOx emission by about 10% with increasing fuel oil consumption, 1.4% in a large diesel engine.

• Journal of Advanced Marine Engineering and Technology
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• 제22권2호
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• pp.248-256
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• 1998

The effects of fuel injection system on the performance in a V8-type diesel engine was stuided in this paper. Fuel injection system is important factor which influence the engine performance and exhaust emission bcasuse the properties in the injected fuel depend on the atomization characteristics. In this study using diesel engine of 17.7:1 compression ration the engine performance and exhaust emission are measured experimentally according to 1000, 1400, 2200rpm in the full-load conditions. The chosen parameters for the major system are such diameter shape of combustion chamber and intake system. The results are as follows: As the nozzle hole diameter and injection angle become smaller and as the injection timing gets advanced the fuel consumption and concentration of smoke are decreasing whereas concentration of $NO_{x}$ is increasing. Andconcentration of $NO_{x}$ is increasing in accordance with the increase of injection pipe diameter and nozzle protrusion. Also it is shown that re-entrant type combustion chamber is more effective than that of toroidal type in the improvement of $NO_{x}$ reduction.