• 한국자동차공학회논문집
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• 제11권6호
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• pp.73-79
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• 2003

The characteristics of NOx emission in multi fuel/air staged combustor have been experimentally studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 ㎿) in a laboratory furnace and Liquefied Petroleum Gas(LPG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, primary/secondary air ratio, primary swirl intensity and secondary swirl intensity for reducing NOx emission. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• 대한기계학회논문집B
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• 제28권4호
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• pp.389-394
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• 2004

An experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is a act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel bums. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as a primary and secondary fuels. This study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• Journal of Advanced Marine Engineering and Technology
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• 제13권4호
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• pp.33-39
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• 1989

A turbulent premixed flames of layer formed between burned hot gas and unburned mixture were investigated by means of schlieren photograph with fluctuations of temperature and ion current. The combustion intensity between burned hot gas and shear layer was higher than the intensity between unburned mixture and shear layer. A wrinkled laminar flame and flamelet were appeared at downstream to exist and distributed reaction zone was at upstream as a result of analyzed probability density functions of temperature fluctuation. The initial combustion intensity of reaction zone of eddy between burned hot gas and shear layer was higher than that of final, flowing downstream, and vice versa between unburned mixture and shear layer.

• International Journal of Automotive Technology
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• 제5권3호
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• pp.165-172
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• 2004

Phenomenological models for direct injection diesel engine emissions including NO, soot, and HC were implemented into a full engine cycle simulation and validated with experimental data obtained from representative heavy-duty DI diesel engines. The cycle simulation developed earlier by Jung and Assanis (2001) features a quasi-dimensional, multi-zone, spray combustion model to account for transient spray evolution, fuel-air mixing, ignition and combustion. In this study, additional models for HC emissions were newly implemented and the models for NO, soot, and HC emissions were validated against experimental data. It is shown that the models can predict the emissions with reasonable accuracy. However, additional effort may be required to enhance the fidelity of models across a wide range of operating conditions and engine types.

• 대한기계학회논문집
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• 제18권7호
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• pp.1789-1798
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• 1994

This paper aimed for numerical simulation of complicated gas turbine combustor with swirler. For the convenience of numerical analysis, fuel nozzle and air linear hole areas of secondary and dilution zone, which are issued to jet stream, were simplified to equivalent areas of annular type. In other to solve these problems, imaginary source terms which are corresponded to supplied fuel amount were added to those of governing equation. Chemical equilibrium model of infinite reaction rate and $k-{\epsilon}-g$ model with the consideration of density fluctuation were applied. As the result, swirl intensity contributed to mixing of supplied fuel and air, and to speed up the flame velocity than no swirl condition. Temperature profiles were higher than experimental results at the upstream and lower at the downstream, but total energy balance was accomplished. As these properties showed the similar trend qualitatively, simplified simulation method was worth to apply to complicated combustor for predicting combustion characteristics.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.161-166
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• 2001

An Experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• 한국항공운항학회지
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• 제23권4호
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• pp.1-5
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• 2015

In this work, a study was conducted to investigate the effect of diaphragm thickness on the regression rate of the hybrid rocket motor. To observe the flow pattern and the recirculation zone, visualizations of combustion chambers with different diaphragm thickness (5mm, 10mm) were performed. It was found that the case with 5 mm thickness had a larger recirculation zone and therefore, had a higher regression rate than the case with 10mm thickness due to the increased residence time and heat transfer toward the fuel surface. Finally, it was concluded that the thickness of diaphragm can be a critical parameter for the enhancement of the regression rate.

• 한국자동차공학회논문집
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• 제3권6호
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• pp.78-86
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• 1995

The structure of premixed turbulent flames in a constant-volume vessel was investigated using a microprobe method. The flame potential signal having one to eight peaks was detected in the case of turbulent flames, each of them being regarded as a flamelet existing in the flame zone. Based on this consideration, the flame propagation speed, the thickness of the flame zone, the number of flamelets and the separation distance between adjacent flamelets in the flame zone were measured. The experimental resuits of this work suggest the existence of "reactant islands" behind the flame front when the turbulence was intensified to some extent. The critical(lowest) ratio of turbulence intensity to the laminar burning velocity being found to be about 0.7 for the formation of reactant islands in this experiment.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.172-179
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• 2001

Experimental studies have been carried out to find out the characteristics of the heat transfer, combustion emission and noise in the boilers without any extra firing zone for complete combustion of fuel. For the experiments a burner of premixed type and some heat exchangers were designed and manufactured. Also test facilities including a data acquisition system and various measuring devices were set up in order to measure automatically the various temperatures and flow rates of water and combustion gas. Various experiments were performed to find out the heat transfer characteristics as well as combustion emission and noise. In general, the burner which has uniform holes in the burner nozzle plate generates big combustion noise . whistling. The noise reduction method is discussed in this study. Many experimental data such as noise level, the amount of pollutant emission and heat transfer rate for different combination of heat exchangers are given as comparison bases for numerical studies.

• 대한기계학회논문집
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• 제19권8호
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• pp.2030-2038
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• 1995

In this study, three turbulent flame propagation models are compared using experimentally measured data of a 4 valves/cylinder spark-ignition engine. First two conventional models are B.K model and GESIM combustion model. The burning rates calculated from the two models are compared with the burning rates calculated from measured pressure data using the one-zone heat release analysis. GESIM combustion model predicts burning rates closer to the data acquired from the experiment in wide operating ranges than B-K model does. The third model is refined based on GESIM combustion model by including the effect of flame stretch, turbulent length scale band pass filter and a variable that considers flame size and the area of flame contacting the cylinder wall surface. The refined combustion model predicts burning rates closer to experimental results than GESIM combustion model does. Also, the refined combustion model predicts flame radius close to the experimental result measured by using optical fiber technique.