• 한국수산과학회지
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• 제9권1호
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• pp.74-78
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• 1976

연료분사시기와 회전속도를 일정하게 했을때 3종류의 연료를 사용하여 압축비와 기관의 성능관계를 조사한 결과 다음과 같은 것이 밝혀졌다. 1. 4 cycle디젤기관의 압축비는 기관마력과 연료소자율과의 관계에서 A, B, C 3종류의 연료에 대해 각각 16, 18, 19의 최적압축비가 존재했으며, 이보다 압축비를 높이면 오히려 기관성능이 저하하고 최대출력도 감소한다. 2. 매시공급열량을 일정하게 했을때 연료 A, B에 대해서 16, 18의 최적압축비가 존재했으며 연료 C에 대해서는 정할수 없었다. 따라서 저 cetane number의 연료에서는 출력에 관계없이 가장 좋은 압축비는 결정할 수 없었다. 3. 발화지연은 압축비가 높을 수록 작았고, 감소율은 압축비가 클수록 작았다.

• 항공우주시스템공학회지
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• 제16권5호
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• pp.17-25
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• 2022

액체로켓엔진의 중요한 특성인 연소 안정성, 연소효율 및 넓은 범위의 추력 조절 등에서 장점이 많은 핀틀 분사기를 설계 및 제작하여 초임계 조건에서 연소시험을 수행하였다. 핀틀 분사기는 추력 제어 및 제작성을 고려하여 직사각형의 1열 형상의 오리피스를 갖는 핀틀 분사기로 제작하였다. 핀틀 분사기의 연소성능 및 상용 분사기로써의 가능성을 검증하기 위해 TMR(Total Momentum Ratio)과 BF(Blockage Factor)를 변화하여 연소 특성을 분석하였다. 연소시험 결과 열유속은 TMR 증가에 따라 증가하는 경향이 나타났으며, 특성속도 효율은 TMR보다 BF에 영향을 받는 것으로 확인되었다. 따라서 TMR 변화에 둔감한 효율 특성을 갖는 1열 핀틀 분사기는 낮은 연료 차압 조건에서 높은 효율을 달성할 수 있다면, 가변 핀틀 분사기 설계 유연성이 높아질 수 있다.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.97-104
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• 2015

This study is a part of the high pressure injection system development on the Turbo GDI engine in order to reduce smoke emission in case of using the low volatile(high DI) fuel which is used as normal gasoline fuel in the US market. Firstly, theoretical approach was done regarding gasoline fuel property, performance, definition of particle matters and its creation as well as problems of the high DI fuel. In this experimental study, 2L Turbo GDI engine was selected and optimized system parameter was inspected by changing fuel, fuel injection mode (single/multiple), fuel pressure, distance between injector tip and combustion chamber, start of injection, intake valve timing in engine dyno at all engine speed range with full load. In case of normal gasoline fuel, opacity was contained within 2% in all conditions. On the other hands, in case of low volatile fuel (high DI fuel), it was confirmed that the opacity was rapidly increased above 5,000 rpm at 14.5 ~ 20 MPa of fuel pressure and there were almost no differences on the opacity(smoke) between 17 MPa and 20 MPa fuel pressure. According to the SOI retard, smoke decrease tendency was observed but intake valve close timing change has almost no impact on the smoke level in this area. Consequently, smoke decrease was observed and 16% at 6000rpm respectively with injector washer ring installed. By removing injector washer to make injector tip closer to the combustion chamber, smoke decrease was observed by 46% at 5,500 rpm, 42% at 6,000 rpm. It is assumed that the fuel injection interaction with cylinder head, piston head, intake and exhaust valve is reduced so that impingement is reduced in local area.

• 한국자동차공학회논문집
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• 제22권6호
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• pp.96-103
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• 2014

Liquefied Petroleum Gas(LPG) has attracted attention as a alternative fuel. The lean-burn LPG direct injection engine is a promising technology because it has an advantage of lower harmful emissions. This study aims to investigate the effect of combustion strategy and excess air ratio on combustion and emission characteristics in lean-burn LPG direct injection engine. Fuel consumption and combustion stability were measured with change of the ignition timing and injection timing at various air/fuel ratio conditions. The lean combustion characteristics were evaluated as a function of the excess air ratio with the single injection and multiple injection strategy. Furthermore, the feasibility of lean operation with stratified mixture was assessed when comparing the combustion and emission characteristics with premixed lean combustion.

• 한국항공우주학회지
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• 제46권7호
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• pp.567-574
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• 2018

스월은 연료의 후퇴율 증가뿐 아니라 연소 압력의 진동을 감소시키며, 하이브리드 로켓의 연소안정화에 기여하는 것으로 알려져 있다. 따라서 스월 산화제 분사에 의한 주연소실 내부의 유동 구조의 변화를 이해하고 연소안정화의 물리적 과정을 실험적으로 연구하였다. 결과에 의하면, 스월은 주연소실의 유동 구조를 변화시켜 후연소실의 500Hz 대역 p'과 q'의 발생을 억제할 뿐 아니라 두 진동의 위상차를 변화하여 상호결합(coupling)에 영향을 주고 있음을 확인했다. 또한 후연소실 화염 가시화를 통하여 스월에 의한 선회운동량의 증가로 와류발생과 흘림 등이 변화하여 연소안정화에 기여하는 것으로 분석됐다.

• Journal of Biosystems Engineering
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• 제35권4호
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• pp.239-243
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• 2010

Biodiesel (BD) can be effectively used as an alternative fuel in diesel engines. However, BD may affect the performance and exhaust emissions in diesel engines because it has different physical and chemical properties from diesel fuel such as viscosity, compressibility and so on. To investigate the effect of injection timing on the characteristics of engine performance and exhaust emissions with BD in an indirect injection diesel engine, BD derived from soybean oil was applied in this study. The engine was operated at six different injection timings from TDC to BTDC $12^{\circ}CA$ and five loads at various engine speeds. Below BD 30, there's similar trend compared with diesel fuel. But, the best injection timing was $4{\sim}6^{\circ}CA$ retarded compare with diesel fuel using BD 30. When the fuel injection timing was retarded, better results were showed, which may confirm by advantages of BD.

• 한국자동차공학회논문집
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• 제22권1호
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• pp.183-192
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• 2014

In this work, the mixture formation and atomization characteristics of biodiesel fuel were reviewed under various test conditions for the optimization of compression-ignition engine fueled with biodiesel. To achieve these, the effect of nozzle caviting flow, group-hole nozzle geometry and injection strategies on the injection rate, spray evolution and atomization characteristics of biodiesel were studied by using spray characteristics measuring system. At the same time, the fuel heating system was installed to obtain the effect of fuel temperature on the biodiesel fuel atomization. It was revealed that cavitation in the nozzle orifice promoted the atomization performance of biodiesel. The group-hole nozzle geometry and split injection strategies couldn't improve it, however, the different orifice angles which were diverged and converged angle of a group-hole nozzle enhanced the biodiesel atomization. It was also observed that the increase of fuel temperature induced the quick evaporation of biodiesel fuel droplet.

• 한국분무공학회지
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• 제22권3호
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• pp.109-115
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• 2017

The aim of this study is to investigate the effect of physical properties of fuels on spray characteristics in the gasoline direct injection system. Injection rate, spray visualization, and spray pattern experiments were performed to analyze the spray characteristics of ethanol, gasoline, and ethanol/gasoline blends. We measured injection rate of each fuel via the Bosch method. The spray visualization experiment was also carried out at atmospheric pressure using a high-speed camera. Finally, the average of drop surface area per unit volume was measured using the optical patternator. The experimental results from Bosch method showed that peak injection rate increased when the volume fraction of ethanol increased. In addition, higher viscosity of ethanol than that of gasoline leads to longer injection delay. At the initial injection region before reaching 0.8 ms, the spray tip penetration becomes longer as increasing the volume fraction of ethanol, but reversely shorter after 0.8 ms. It was found that ethanol makes spray angle become larger. The surface area per unit volume of the drop was decreased as the distance from the injection tip or the concentration of the gasoline increased.

• Journal of Advanced Marine Engineering and Technology
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• 제35권6호
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• pp.820-828
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• 2011

에너지 절약은 해상운송분야에서 이익을 내기 위한 가장 중요한 요인 중 하나이다. 연료 소비율을 낮추기 위해서는 가능한 한 선박의 추진효율을 높여야만 한다. 추진효율은 추진기관과 낮은 회전속도에서 더 좋은 효율을 갖는 프로펠러의 조합에 의존한다. 기관은 저속이 될수록 연료분사과정에서의 지연시간으로 인해 회전 토크 변동이 심해진다. 본 연구에서는 강인 제어이론을 적용하여 강인 안정성과 강인 성능을 고려한 기관 속도제어기들, 즉 준최적 $H_{\infty}$제어기, $H_{\infty}$루프-성형 제어기 및 ${\mu}$-제어기를 설계한다. 컴퓨터 시뮬레이션 결과로부터 이들 3가지 제어기의 타당성을 검토한다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 추계학술발표회
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• pp.133-137
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• 2007

An experimental study is conducted to evaluate and compare the use of BiodieseDI Fuel supplements at blend ratio of 10/90(BDF10) and 20/80(BDF20), in four stroke, direct injection diesel engine located at the authors' laboratory. especially this Biodiesel is produced from Rape oil at the authors' laboratory. The tests are conducted using each of the above fuel blends, in the engine working at a speed of 1800rpm and at a various loads. In each test, specific fuel consumption, exhaust emissions such as nitrogen oxides(NOx), carbon monoxide(CO) and Soot are measured. The results of investigation at various operating conditions are as follows (1) Specific fuel consumption is increased average 1.52%, maximum 1.84% at load 25% in case of BDF10, and average 1.98%, maximum 2.80% at load 25% in case of BDF20. (2) CO emission is decreased average 5.14%, maximum 6.09% at load 0% in case of BDF10, and average 7.75%, maximum 9.13% at load 0% in case of BDF 20. (3) NOx emission is increased average 2.97%, maximum 3.74% at load 0% in case of BDF10, and average 3.84%, maximum 4.67% at load 0% in case of BDF20. (4) Soot emission is decreased average 9.36%, maximum 10.85% at load 75% in case of BDF10, and average 11.99%, maximum 13.95% at load 75% in case of BDF20.