• Journal of the Korean Society of Safety
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• v.7 no.3
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• pp.14-21
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• 1992

The smouldering combustion of cellulose insulation treated with boric acid-borax-alum as combustion retardants are examined by Candle type combustibility tester. This sequence was examined quantitatively for longitudinal cylinder bed of cellulose insulation. Two configuration are possible, downward and upward smoulder spread ; both were investigated exprimentally. The smoulder spread velocity of cellulose insulation was 2.5cm/s -5.0cm/s in smoulder region. As results of critical oxygen content measurement, the effectiveness of alum as third combustion retardant are acceptable for flaming retardant effect. The phenomena of combustion transition are governed by quantity of commbustible gas generation In heating zone of cellulose insulation. The critial oxygen content are decreased with the increase of gas flow rate.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.309-311
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• 2015

The MILD(Moderate or Intense Low-oxygen Dilution) combustion has been considered as one of the promising combustion technology for high thermal efficiency and low emissions. In this paper, the effect of fuel oxygen impingement on formation of MILD combustion was analyzed using numerical simulation. This investigation was simulated under the thermal intensity $0.04MW/m^3$ and equivalence ratio 0.91. The results show that the temperature distribution was become relatively uniform and the amount of CO emission was decreased as the increase of oxygen jet velocity and impinging angle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.255-258
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• 2004

In order to provide a useful data for combustion chamber design, a numerical analysis for spray combustion of liquid fuel and oxidizer in combustion chamber has been conducted. High temperature nitrogen gas in low speed has been conveyed for the ignition of the liquid fuel and oxidizer mixture. Temperature and velocity distributions affected by characteristics of liquid fuel and oxidizer combustion have been investigated.

• Journal of Aerospace System Engineering
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• v.3 no.4
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• pp.41-49
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• 2009

This paper present result of numerical simulation of premixed combustion around a triangle Bluff Body. And a numerical simulation of a premixed flame stabilization by a bluff body was performed using LES Model. The calculated results from the LES showed a good agreement with experiment data than k-model. Premixture combustion has flammability limit, quenching distance, smallest ignition energy has the combustion quality of the back. Bluff body makes a recirculation zone. Therefor velocity of behind bluff body is very slow. It was caused by slowly position speed and the fire occurred after the Bluff Body. Occurrence of fire it made the waste gas of high speed and the thrust made well.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.9
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• pp.1284-1291
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• 2002

Combustion instabilities are an important concern associated with lean premixed combustion. Laboratory-scale dump combustor was used to understand the underlying mechanisms causing combustion instabilities. Experiments were conducted at atmospheric pressure and sound level meter was used to track the pressure fluctuations inside the combustor. Instability maps and phase-resolved OH chemiluminescence images were obtained at several conditions to investigate the mechanism of combustion instability and relations between pressure wave and heat release rate. It showed that combustion instability was susceptible to occur at higher value of equivalence ratio (>0.6) as the mean velocity was decreased. Instabilities exhibited a longitudinal mode with a dominant frequency of ∼341.8 Hz, which corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase when instabilities occurred. Rayleigh index distribution gave a hint about the location where the strong coherence of pressure and heat release existed. These results also give an insight to the control scheme of combustion instabilities. Emission test revealed that NOx emissions were affected by not only equivalence ratio but also combustion instability.

• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.24-29
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• 2003

Numerical analysis was conducted to predict the damage of indoor gas explosion for the propagation of explosion flame. Indoor gas diffusion distribution due to gas leakage was obtained by diffusion equation that adopted initial conditions from reference. Enthalpy of each gas-mixture ratio and reduced mechanism was applied to calculate flame temperature, and laminar combustion velocities with the variant of each gas concentration from reference were applied to the gas mixture. Turbulent combustion velocity was modeled by coupling of turbulent energy and laminar combustion velocity in k-$\epsilon$ model. For the analysis of flame propagation cartesian and cylindrical coordinate were used to indoor position and flame propagation respectively. The study analyzes the cause of pressure rising with the variation of flame propagation by glass damage, and the result shows that indoor pressure rising with ignition position varies window dimension.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.215-220
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• 2005

When the fuel jet velocity is smaller than coflow velocity, the trend of decreasing liftoff height of highly diluted propane lifted flame with coflow velocity is observed experimentally. To investigate the mechanism of decreasing liftoff height with coflow velocity, lifted flames in propane jet has been studied numerically. Using one-step overall reaction mechanism the liftoff heights have been calculated for four cases of coflow velocity. The simulation agrees qualitatively with experimental observation that the liftoff height decreases with coflow velocity. As coflow velocity increases, the streamlines between nozzle and lifted flame diverge in radial direction due to the difference of momentum between coflow jet and fuel jet such that the local flow velocity ahead of lifted flame base decreases resulting in decrease of the liftoff height with coflow velocity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.2
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• pp.97-107
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• 2017

This study is the second investigation on the steady flow characteristics of an SI engine with a semi-edge combustion chamber as a function of the port shape with varying evaluation positions. For this purpose, the planar velocity profiles were measured from 1.75B, 1.75 times of bore position apart from the bottom of head, to 6.00B positions using particle - image velocimetry. The flow patterns were examined with both a straight and a helical port. The velocity profiles, streamlines, and centers of swirl were almost the same at the same valve lift regardless of the measuring position, which is quite different from the case of the pent-roof combustion chamber. All the eccentricity values of the straight port were out of distortion criterion 0.15 through the lifts and the position. However, the values of the helical port exceeded the distortion criterion by up to 4 mm lift, but decreased rapidly above the 3.00B position and the 5 mm lift. There always existed a relative offset effect in the evaluation of the swirl coefficient using the PIV method due to the difference of the ideal impulse swirl meter velocity profile assumption, except for the cylinder-center-base estimation that was below 4 mm of the straight port. Finally, it was concluded that taking the center as an evaluation basis and the assumption about the axial velocity profile did not have any qualitative effect on swirl evaluation, but affected the value owing to the detailed profile.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.4
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• pp.418-429
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• 1992

Recently, many researchers make a great effort to develop high efficient marine diesel engines using low grade heavy oil, and also study substitution fuel oil for engines and boilers. In case of Fisheries Vessels, we need to know that fish oil can be substituted for fuel oil. Therefore, it is studied that evaporation, ignition and combustion phenomena of the single droplet of fish oils (i.e., Sardine fish oil, File fish oil and Alaska pollac oil) on heated plane surface to evaluate appropriateness as substitution oil. Methanol and light oil are tested simultaneously to help the evaluation on these Fish oils. The results are summarized as follows: 1. The type of evaporation and combustion is spherical evaporation in case of methanol and light oil. And fish oil blended with light oil was finished after spherical evaporation happen when high temperature. 2. Ignition of Pure fish oil was shorter than that of fish oil blended with light oil. 3. Heat transferred to droplet could make qualitative comparison by contact diameter of droplet with hot surface as time changes. Life time of droplet according to the change of heated surface temperature was greatly influenced by droplet contact condition on the heated surface. 4. As far as combustion phenomena was concerned, apparent diameter of the fish oil droplet increased after ignition and decreased suddenly by internal boiling of droplet. 5. Three fish oils had similar phenomena on the evaporation, ignition and combustion. 6. Evaporation and combustion feature of fish oil could not be shown by coefficient of evaporation velocity of droplet and coefficient of combustion velocity of droplet.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.87-88
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• 2015