• Journal of the Korean Society of Visualization
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• v.17 no.2
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• pp.67-72
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• 2019

In this study, we investigate the non-reacting and reacting performance of single nozzle for post H class gas turbine by using commercial CFD tool, CONVERGE, based on adaptive mesh refinement. By varying swirl number and mixing length of base nozzle design. Through the numerical analysis, basic phenomena can be well described with respect to fuel concentration for non-reacting flow, temperature distribution, velocity vector and combustion outlet temperature distribution for reacting flow. However, there are rooms for improvements in model accuracy by comparing test results. Comparison between numerical analysis are planning for further study.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.53-59
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• 2015

Combustion characteristics for co-firing of biomass (Walnut Shell) as blending fuel in coal fired boiler have investigated using thermogravimetric analyser (TGA) and drop tube reactor (DTR). The results show that devolatilization and char combustion for WS occurs at lower temperature than those of existing coals and has lower activation energy value, which is resulting in higher reactivity. When the WS is blended with coal, TGA results show linear profiles depending on blending ratio for each fuel. However, DTR results exist the non-additive phenomena for blending of WS. As blending ratio of WS increase, the UBC decrease at BBR 5%, but the UBC rather increase from BBR 10% due to oxygen deficiency formed from rapid combustion of WS. This paper propose that fuel lean condition by oxygen rich lead to higher blending ratio of biomass by solving the oxygen deficiency condition.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.5
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• pp.325-331
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• 2011

A numerical analysis of reactive flow in a MILD(Moderate and Intense Low oxygen Dilution) combustor is accomplished to elucidate the characteristics of combustion phenomena in the furnace with the change of fuel and air nozzle position and air mass flow rate. For the case with the fuel nozzle located near center position of combustor, the reaction zone started at the fuel nozzle and had inclined shape toward combustor wall when the air mass flow rate was relatively smaller. On the other hand, the end of reaction zone moved toward center of combustor from combustor wall when the air flow rate was relatively larger. For the case with the air nozzle located near center position of combustor, the reaction zone started at the fuel nozzle and had inclined shape toward combustor wall when the air mass flow rate was relatively small, which was similar as the previous case with smaller air mass flow rate. On the other hand, the end of reaction zone moved toward combustor wall when the air flow rate was relatively larger. The maximum temperature increased as the air mass flow rate increasing for both cases, and the concentration of thermal NOx increased also from the previous reason of temperature characteristics. The concentration of NOx for the case with the air nozzle located near center position of combustor was considerably smaller than that for the case with the fuel nozzle located near center position of combustor. From the present study, the case with the air nozzle located near center position of combustor and theoretical air flow rate was the most effective condition for the NOx reduction and perfect combustion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1745-1753
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• 2008

We analyzed the physical and chemical properties such as proximate analysis, ultimate analysis, heating values, thermogravimetric analysis, and combustion test for the organic sludge discharged from chemical and petrochemical product manufacturing industries in the industrial complex. The average combustible and ash content of organic sludges from chemical and petrochemical product manufacturing industries were 17.42%, 7.45%, and 18.25%, 4.22%, respectively. The C, H, O, N, and S compositions for chemical and petrochemical product manufacturing industries were 33.06, 4.34, 24.81, 5.18, and 0.72%. And those compositions for petrochemical product manufacturing industries were 36.58, 4.74, 26.79, 5.09, and 0.49%, respectively. From the TGA test, the minimum temperature for combustion of the sludge discharged from B company was $700^{\circ}C$ for direct use for energy and 2 sludges(F and N companies) were about $600^{\circ}C$. According to the basic combustion test, high concentration of CO was formed because oxidation and pyrolysis reaction take place in the batch type reactor at the same time. From this phenomena we could obtain the significant data for the overheating and breakage of furnace.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.2
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• pp.18-24
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• 1999

Liquid ramjet combustor is closely connected with complex phenomena due to a series of processes such as intake air, spray, mixing, and combustion. The present numerical experiments were peformed to investigate these flow characteristics for two and three dimensional liquid ramjet combustor. Grid system was made with three domains: intake region where air is supplied and fuel is injected, combustor and nozzle region, and exit atmosphere region. The numerical results showed that two and three dimensional flow patterns in recirculation region of combustor were significantly different each other and spray model was necessary to predict correctly the chemical reaction flow characteristics. Numerically examined for two different location of fuel injector, one is located on the bottom position of curved intake and the other is located on the top position. We found that bottom position of fuel injector is better than top position because fuel influx to the recirculation region which is need to sustain chemical reaction is more than the latter.

• Journal of Environmental Health Sciences
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• v.34 no.1
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• pp.42-48
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• 2008

The objectives of this study were to measure ambient TGM concentrations in Seoul Korea, to determine the temporal variation of TGM, and to analyze the relationships among TGM, meteorological data and PM2.5 measured at the same time. Ambient TGM and PM2.5 concentrations were measured at the roof of the Graduate School of Public Health building in Seoul, Korea for the period of January to October 2004. Average TGM concentration was $3.43{\pm}1.17ng/m^3$. The average TGM was at a low concentration similar to those of background sites in other countries. The temporal variations and meteorological phenomena of TGM were not statistically significant. There was a positive link between TGM and PM2.5. It didn't indicate that reduction of $Hg^{2+}$ to Hg0 had occurred in liquid water contained in smog as in a previous study, but it shows that PM2.5 and TGM could be emitted from the same sources such as power plants and combustion engines. Also, the strong correlation between TGM and $SO_2$ concentrations indicated that the source of TGM was from fossil fuel combustions including coal combustion. Specifically, $SO_2\;and\;SO_4{^2-}$ concentrations correlated to TGM concentrations could be linked to TGM emitted from local and regional sources as well.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.4
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• pp.52-58
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• 2007

The irregular fuel surface was observed by the visualization of hybrid rocket combustion. Even though the test condition maintained oxidizer rich environment, the irregular dark fuel surface was formed as the result of incomplete combustion. In order to investigate the correlation of the characteristics of oxidizer flow and the irregular fuel surface, various flow conditions were imposed such as swirl flow, induced swirl flow by helical fuel configuration and straight flow. Test results revealed no correlation was found between oxidizer flow condition and irregular fuel surface. And this can be a commonly observed phenomena in the tests with different fuel/oxidizer combination. Thus, the irregular fuel surface can be a result of the interaction of blowing flow of vaporized fuel and the boundary layer of oxidizer flow. A further study will be required to confirm the assumption for the formation of irregular fuel surface.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.26-37
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• 2011

A 75-tonf-class LRE(liquid rocket engine) thrust chamber with ablative material for technology demonstration was manufactured on the basis of development technologies of 30-tonf-class LRE. Hydraulic characteristics of the thrust chamber were examined through cold flow test and ignition test of low flow condition. Test result showed that hydraulic function was good. Side ignition method with igniter ring also showed a fine function of ignition in operating ways of static condition. But a close review is required to understand the phenomena of generation and extinction of specific frequencies showed in dynamic characteristics ways. To achieve these, a large combustion test facility which is capable of performing combustion test at design condition of the 75-tonf-class thrust chamber should be constructed as soon as possible.

• Fire Science and Engineering
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• v.23 no.1
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• pp.55-62
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• 2009

A general combustion characteristics of forcing nonpremixed jet in laminar flow rates have been conducted experimentally to investigate the effect of forcing amplitude with the resonant frequency of fuel tube. There are two patterns of the flame lift-off feature according to the velocity increasing; one has the decreasing values of forcing amplitude on the lift-off occurrence when a fuel exit velocity is increasing, while the other has the increasing values. These mean that there are the different mechanisms in the lift-off stability of forced jet diffusion flame. Especially, the characteristics of attached jet flame regime are concentrically observed with flame lengths, shapes, flow response and velocity profiles at the nozzle exit as the central figure. The notable observations are that the flame enlogation, in-homing flame and the occurrence of a vortical motion turnabout have happened according to the increase of forcing amplitude. It is understood by the velocity measurements and visualization methods that these phenomena have been relevance to an entrainment of surrounding oxygen into the fuel nozzle as the negative part of the fluctuating velocity has begun at the inner part of the fuel nozzle.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.60-65
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• 2004

Numerical simulations and experiments have been carried out to investigate the effect of fuel injection nozzles on the combustion and NOx formation processes in a medium-speed marine diesel engine. Spray visualization experiment was performed in the constant-volume high-pressure chamber to verify the numerical results on the spray characteristics such as spray angle and spray tip penetration. Time-resolved spray behaviors were captured by high-speed digital camera and analyzed to extract the information on the spray parameters. Spray and combustion phenomena were examined numerically using FIRE code. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation processes. Numerical results were verified with experimental data such as cylinder pressure, heat release rate and NOx emission. Finally, the effects of fuel injection nozzles on the engine performance were investigated numerically to find the optimum nozzle parameters such as fuel injection angle, nozzle hole diameter and number of nozzle holes. From this study, the optimum fuel injection nozzle (nozzle hole diameter, 0.32 mm, number of nozzle holes, 8 and fuel injection angle, $148^{\circ}$) was selected to reduce both the fuel consumption and NOx emission. The reason for this selection could be explained from the highest fuel-air mixing in the early phase of injection due to the longest spray tip penetration and the highest heat release rate after $19^{\circ}$ ATDC due to the increased injection duration.