• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.453-456
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• 2011

An experimental investigation of the heat transfer characteristics of stretched premixed flames using Synthetic gas has been performed. Hydrogen and carbon mon-oxide which could be extracted from coal gasification process are the main fuel of synthetic-gas. Heat flux at the stagnation point was increased as global strainrate was increased, then the heat flux was decreased when a global strainrate reached a sudden point. Heat flux at the stagnation point is also affected by nozzle to impingement distance. Heat flux was increased as nozzle to impingement place distance was increased. This study is a foundation study of practical use of secondary gases from coals.

• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2001.04a
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• pp.8-8
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• 2001

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.365-373
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• 2010

A chemical reactor model (CRM) was developed for a jet stirred reactor (JSR) to predict the emission of exhaust such as NOx. In this study, a two-PSR model was chosen as the chemical reactor model for the JSR. The predictions of NO formation in lean premixed methane-air combustion in the JSR were carried out by using CHEMKIN and GRI 3.0 methane-air combustion mechanism which include the four NO formation mechanisms. The calculated results were compared with Rutar's experimental data for the validation of the model. The effects of important parameters on NO formation and the contributions of the four NO pathways were investigated. In the flame region, the major pathway is the prompt mechanism, and in the post flame region, the major pathway is the Zelodovich mechanism. Under the lean premixed condition, the N2O mechanism is the important pathway in both flame and postflame regions.

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.15-21
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• 2013

This study evaluated comparison of the risk according to the type of fuel by three-dimensional simulation tool(FLACS). The consequence analysis of fire explosion and jet-fire was carried out in the layout of a typical high-pressure gas filling stations using CNG, hydrogen and 30%HCNG. Under the same conditions, hydrogen had a 30kPa maximum overpressure, CNG had a 0.4kPa and HCNG had a 3.5kPa. HCNG overpressure was 7.75 times higher than the CNG measurement, but HCNG overpressure was only 11.7% compared to hydrogen. In case of flame propagation, hydrogen had a very fast propagation characteristics. On the other hand, CNG and HCNG flame propagation velocity and distance tended to be relatively safe in comparison to hydrogen. The estimated flame boundary distance by jet-fire of hydrogen was a 5.5m, CNG was a 3.4m and HCNG was a 3.9m.

• Fire Science and Engineering
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• v.19 no.3 s.59
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• pp.58-63
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• 2005

Experimental measurements of flames and the product properties were performed for small kerosene pool fires. which is widely used as a fire source of laboratory scale experiments with scaling modeling. The flame length and flickering frequency were investigated for the flame structures, and compared with the theory. Three measurement methods were introduced to clarify the smoke characteristics, i.e. various gas concentrations, smoke density and thermophoretic sampling with transmission electron microscopy (TEM). The yield of carbon dioxide and the consumption of oxygen were proportional to the heat release rate of pool fires, but there is no trend on carbon monoxide emission. Smoke density of turbulent flames was exponentially increased with the heat release rate. The morphology of the soot particle was investigated to address the degree of soot maturing. The results show that the similar smoke morphology between an inverse jet flame and a pool fire exists despite of different combustion controlling mechanisms.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.1-8
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• 2016

An experimental study was performed for the combustion-field visualization of the burner which burns the liquid hydrocarbon fuel atomized by an ultrasonic oscillator. Configurations of the flame and combustion-field were caught by both high-speed camera and thermo-graphic camera, and those images were analyzed in detail through a post-processing. As a result, the combustion-field grew and reaction-temperature rose due to the strengthening of combustion reaction with the increasing flow-rate of carrier-gas. In addition, a phenomenon of flame flickering was discussed through the comparative analysis of the variational behaviors between the visible flame and IR (Infrared) flame-field.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2372-2377
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• 2007

Characteristics of turbulent lifted flames in coflow jets with the varying initial temperature have recently been investigated about only propane case diluted by nitrogen. The investigation has firstly improved a premixed flame model and a large scale mixing model among competing theories on the stabilization mechanism of turbulent flame to be suitable for a high temperature condition. In this research, about methane with good availability to apply for a practical combustor as clean fuel, its characteristics of turbulent nonpremixed flame have been studied experimentally. The results have shown an effectiveness of the premixed flame model and the large scale mixing model considered initial temperature variation. Additionally, considering the axial distance where the mean fuel concentration falls below the stoichiometric level along the center line of the jet according to diluting nitrogen, the premixed flame model have more accurately been improved.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.494-498
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• 2001

When supersonic jet impinges on wall from the nozzle, complex flow pattern appears such as Mach disc, expansion fan, and jet boundary. The numerical computation of this supersonic jet is important on flame deflecctor design for launch space especially. In this paper, we analyzed supersonic jet structure impinging on deflector wall using three dimensional steady and unsteady compressible equation and showed temperature and pressure distribution on the wall surface. As a result, some dominant factors of jet flows are discussed for conceptual design of flame deflector.

• Journal of computational fluids engineering
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• v.8 no.3
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• pp.7-11
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• 2003

Accurate assessment of the effect of jet plume on the boattail pressure drag of transonic airbreathing missiles is very important to reduce drag and to satisfy the flight range and the required maneuver. Numerical results of drag analysis for boattail and base pressures due to jet plume are presented considering the turbulence modeling. Drag assessment due to the size of jet plume, the conditions of the exhaust gas, the configurations of the boattail, and transonic mach numbers is included.