• The Korean Journal of Ceramics
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• 제6권3호
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• pp.250-257
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• 2000

The feasibility of synthesizing SiC-AlN solid solution by field-activated combustion synthesis was demonstrated. At lower fields of 8-16.5V/cm, composites of AlN-rich and SiC-rich phases were synthesized, but at fields of 25-30 V/cm, the product was a 2H structure solid solution. Combustion synthesis of the solid solution by nitridation of aluminum with silicon carbide under a nitrogen gas pressure of 4-8 MPa was also investigated. The maximum combustion temperature and wave propagation velocity were found to be influenced by the electric field in the field-activated combustion synthesis, and by the green density and nitrogen pressure in the combustion nitridation. In both cases the formation of solid solutions is complete within seconds, considerably faster than in conventional methods which require hours.

• 오토저널
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• 제10권5호
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• pp.42-53
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• 1988

The effects of ignition position on combustion in a chamber with swirl flow were investigated by use of hot wire anemometer, high speed schlieren photography, and chamber pressure measurement. In experiments, the closed-constant volume combustion chamber was used, and the swirl was formed unsteadily by suction of external fluid after reducing pressure in the chamber. Results show that the effect of ignition position on combustion depends on the flow state and the flame propagation distance corresponding to each ignition position. Also, the effect of combustion promoting increases as an ignition position moves from the center of chamber to the outside, but maximum burning pressure was obtained at the position that is the shortest flame propagation distance.

• 대한기계학회논문집
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• 제11권3호
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• pp.362-367
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• 1987

본 연구에서는 위의 인자들 중 .int.Pdt대신에 계산의 편의상 .int.Pd.theta.로, .DELTA.P는 최고압력차의 영향이 가장 크다고 생각되어 (.DELTA.P)$_{max}$를 대상으로 하여 이들 제인 자와 각 주파수성분과의 상관관계에 대하여 검토하고, 주파수역에 대하여 미치는 영향 을 정량적으로 해석하기 위하여 보조 프로그램을 작성하였다.

• International Journal of Automotive Technology
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• 제6권2호
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• pp.79-85
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• 2005

This work is to investigate the surface heat flux and combustion characteristics of premixed propane mixture in a constant volume chamber. The experiment of heat flux and combustion characteristics of premixed propane mixture are performed with various equivalence ratio and initial pressure conditions. Based on the experimental results, it is found that the maximum instantaneous temperature is increased with the increase of initial pressure in the chamber. There are significant differences in the burning velocity of premixed propane mixture at different measuring points in the constant volume combustion chamber. A]so, the trends of temperature difference at each measuring points are similar to the burning velocity in the combustion chamber. It is concluded that the total heat loss during the combustion period is affected by the equivalence ratio and the initial condition of fuel-air mixture.

• 한국분무공학회지
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• 제19권4호
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• pp.211-215
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• 2014

The main purpose of this study is to provide basic information of droplet soot generation of decane fuel. To achieve this, this paper presents the experimental results on the decane droplet combustion conducted under various ambient pressure($P_{amb}$), and oxygen concentration($O_2$) conditions. At the same time, the experimental study was conducted in terms of soot volume fraction($f_v$) and its maximum value. Also, visualization of single fuel droplet was conducted by high resolution CCD camera and ambient pressure($P_{amb}$) and oxygen concentration($O_2$) was changed by control system. It was revealed that higher ambient pressure($P_{amb}$), and oxygen concentration($O_2$) enhanced the soot generation and improved the maximum soot volume fraction( $f_v$).

• Journal of Advanced Marine Engineering and Technology
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• 제24권4호
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• pp.421-426
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• 2000

A study on the combustion and exhaust emissions characteristics of diesel engine with various suction air humidity is performed experimentally. In this paper, suction air humidity is changed from RH 50% to RH 90%, the experiments are performed at engine speed 1800rpm, and main measured parameters are cylinder pressure, fuel consumption rate, CO, HC, NOx and Soot emissions etc. Increase of suction air humidity from RH 50% to RH 90% does not effect specific fuel consumption, decreases maximum pressure in cylinder, ratio of maximum pressure rise and net heat release, and delays ignition timing. Also, that increases CO and HC emissions, decreases NOx emissions, but does not constant in changing tendency on emission.

• 수산해양기술연구
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• 제55권4호
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• pp.411-418
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• 2019

In this study, to investigate the effect of physical and chemical properties of butanol on the engine performance and combustion characteristics, the coefficient of variations of IMEP (indicated mean effective pressure) and fuel conversion efficiency were obtained by measuring the combustion pressure and the fuel consumption quantity according to the engine load and the mixing ratio of diesel oil and butanol. In addition, the combustion pressure was analyzed to obtain the pressure increasing rate and heat release rate, and then the combustion temperature was calculated using a single zone combustion model. The experimental and analysis results of butanol blending oil were compared with the those of diesel oil under the similar operation conditions to determine the performance of the engine and combustion characteristics. As a result, the combustion stabilities of D.O. and butanol blending oil were good in this experimental range, and the indicated fuel conversion efficiency of butanol blending oil was slightly higher at low load but that of D.O. was higher above medium load. The premixed combustion period of D.O. was almost constant regardless of the load. As the load was lower and the butanol blending ratio was higher, the premixed combustion period of butanol blending oil was longer and the premixed combustion period was almost constant at high load regardless of butanol blending ratio. The average heat release rate was higher with increasing loads; especially as butanol blending ratio was increased at high load, the average heat release rate of butanol blending oil was higher than that of D.O. In addition, the calculated maximum. combustion temperature of butanol blending oil was higher than that of D.O. at all loads.

• Tribology and Lubricants
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• 제24권3호
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• pp.133-139
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• 2008

In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated the effects on the film pressure distribution due to the change in maximum combustion pressure.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.37-45
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• 1995

Effect of reentrant type bowl geometry on combustion characteristics was investigated in a D.I. diesel engine. The main factor was the cupola height of bowl center and the reentrant angle of combustion chamber, and the cylinder pressure, engine performance and emissions of the engine using the total 11 kinds of the combustion chamber were measured by test. The results are as follows. The NOx decreases by increasing the cupola height of bowl center because it makes the decreasing of maximum combustion pressure by the heat loss and smooth combustion from good airflow. The smoke increases by increasing the reentrant angle at high speed range of the engine, but decrease at low and medium speed range until the reentrant angle becomes $15^{\circ}$.

• 에너지공학
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• 제11권2호
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• pp.178-185
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• 2002

본 연구의 목적은 조기 연료 기화장치가 승용차의 냉간 주행성능에 미치는 영향을 조사하여 평가하는 것이다. 이를 위해 실험은 냉 시동성과 냉간 주행성능으로 나누어 실시하여 연료소비율과 유해 배출 가스량을 측정하고, 실린더내의 연소압력을 근거로 열 발생율, 적산 열 발생량, 질량연소율을 구하였다. 결과는 다음과 같다. 조기연료 기화장치의 장착은 냉 시동 초기부터 난기 완료까지의 연료소비량을 17.7%향상, 냉 시동 초기의 일산화탄소의 배출량은 23%, 탄화수소 배출량은 45% 저감 되고, 또한 냉간 주행시의 엔진의 연소 최고압력, 도시 평균 유효압력의 변동을 4∼6% 개선시키고, 단위 출력당 연료 소비율이 0.2∼2.3% 절감된다. 이것은 조기연료기화장치에 의한 연소실내 최대 열 발생 지연기간 및 주 연소기간이 짧아지기 때문이다.