• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.66-74
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• 1996

Numerical simulations were carried out using standard Reynolds stress turbulence model(LRR model) and modified RSM(Janicka model ) to validate these models in combustion flow fields. Two flames were selected for use as a benchmark data for model testing. One is a conventional jet diffusion flame that has the effect of suppression of turbulence by combustion. The other is a triple jet diffusion flame that designed to give high turbulence to the periphery of the flame and to remove the low Reynolds-number flow fields. As a result, it was found that the modification of standard RSM model is indispensable in the modelling of flames with low turbulence region. And it is also necessary to improve the existing modified models for the universal use.

• 연구논문집
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• s.31
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• pp.23-43
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• 2001

An experimental investigation on the reduction of nitrogen oxide emission from swirling, turbulent diffusion flames was conducted using multi air staged combustor, The combustor utilizes swirler to dampen fuel/air mixing, allowing an extended residence time for fuel pyrolysis and fuel-N conversion chemistry in an locally fuel-rich environment prior to burnout. This process also allow to reduce thermal NOx formation to lessen the temperature of reaction zone. The aerodynamic process therefore emulates the conventional staged combustion process, but without the need for the physically separate fuel-rich and -lean stages. Parametric studies on the ratios of each staged air and droplet size were carried out the feasibility of fuel/air mixing for low NOx combustion with diesel and pyridine mixed diesel fuel oil.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.76-80
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• 2012

Uni-element preburners using a oxidizer-rich triplex injector have been designed and tested. During combustion tests 1L mode high-frequency instability of 1100 Hz and low-frequency instability of 100 Hz were observed. High-frequency instability has been suppressed by reducing chamber diameter and applying turbulent rings in combustion chamber. Recently, research to reduce low-frequency instability is in progress.

• Journal of ILASS-Korea
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• v.23 no.4
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• pp.169-174
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• 2018

In this work, optimization of blade shape for the improvement of mixture formation and vortex of intake port was performed by numerically, and the combustion performance of CI engine with optimized blade shape was investigated. To achieve this, 3 types of blade shape were studied under the different air flow mass conditions and the numerical results were investigated in terms of humidification water, moisture concentration, and velocity distributions. Evaporated liquid mass was also compared under various test conditions to reveal the turbulent intensity in an intake port. It was observed that the optimized blade shape can improve the humidification water, moisture concentration, and velocity distributions of intake port inside. The evaporated liquid mass was also increased under the conditions with blade. Especially, low NOx emissions was observed with optimized blade condition.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.2
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• pp.34-44
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• 1985

Swirling flows have commonly used for a number of years for the stabilization of high- intensity combustion processes. In general, these swirling flows are poorly understood because of their complexity. This paper, therefore, deals with the experimental study on turbulent diffusion flames with swirling flow in unburned flow field by using a model combustor. The purpose of this study is to investigate quantitatively the swirling air jets issuing from vane swirlers. The fundamental experiments have been performed for the local velocity distribution, turbulence intensity and Schlieren photograph in th jets issuing into the atmosphere.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.76-84
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• 2000

A numerical study was conducted for the investigation of thermal choking process in a model scramjet engine based on the experimental results at the Australian National University. The results of numerical simulation showed that thermal choking process could be related to the interaction between hypersonic flow and fuel-air mixing process. Especially, we could make sure that turbulent mixing was most important parameter to the thermal choking process.

• Journal of the Korean Society of Visualization
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• v.16 no.1
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• pp.37-41
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• 2018

The two-fluid model is widely used for practical applications involving multi-phase flows in chemical reactor, nuclear reactor, desalination systems, boilers, and internal combustion engine. There are several modeling terms in the two-fluid model, which must be determined properly. This study suggests the best models for turbulent vertical bubbly flow.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.317-318
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• 2015

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.17-24
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• 2016

The reacting flows of gaseous hydrogen/liquid oxygen 2D coaxial shear injector with varying recess length are numerically analyzed. The standard ${\kappa}-e$ model and laminar flamelet model are adopted for the steady turbulent combustion with the ideal and real gas equations. As the recess length increases, the recirculating region in the combustion chamber expands and the vorticity is intensified. Also, the variations of temperature, products, and pressure are strongly related to the recess length. The results show that an efficient combustor can be obtained by the introduction of the recessed injector.

• Journal of the Korean Society of Combustion
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• v.13 no.2
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• pp.1-6
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• 2008

An experimental study of the flame response in a turbulent premixed combustor has been conducted with room temperature, atmospheric pressure inlet conditions using premixed natural gas. The fuel is premixed with the air upstream of a choked inlet to avoid equivalence ratio fluctuations. Therefore the observed flame response is only the result of the imposed velocity fluctuations, which are produced using a variable speed siren. Measurements are made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results are analyzed to determine the phase and gain of the flame transfer function as a function of the modulation frequency. Of particular interest is the effect of flame structure on the flame response predictions and measurements. The results show that both the gain and the phase of flame transfer function are closely associated with the flame length and structure, which is dependent upon the upstream flow perturbation as well as equivalence ratio in the current study.