• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.247-253
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• 2004

As a large scale port development in coastal waters proceeds step by step and populations in the vicinity of port are getting increased, the issue on "how to dispose the treated municipal water and wastewater in harbor" brings peoples′ concern. The submarine outfall system discharges the primary or secondary treated effluent at the coastline or in deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding sea water and becomes very dilute. We intended in this paper to investigate the impact on dilution of effluent and the behavior of flume under the conditions of the seasonal and spatial temperature variations, which have not been noticeable in designing effective marine outfall system. To predict and analyze the behaviour and dilution characteristics of plume not just with the effluent temperature, but also with the seasonal variation of temperature of surround water and tidal changes, CORMIX(Cornell Mixing Zone Expert System)-GI have been applied. The results should be used with caution in evaluation the mixing zone characteristics of discharged water. We hope to help for the effective operation of outfall system, probable outfall design, protection of water quality, and warm water discharges from a power plant, etc.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.85-92
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• 2004

As a research to develop a SCRAM jet engine is actively conducted, a necessity to produce a high-enthalpy flow in a laboratory is increasing. In order to develop the SCRAM-jet engine, stabilized combustion in a supersonic flow-field should be attained, in which a duration time of flow is extremely short. Therefore, a mixing process of breathed air and fuel, which is injected into supersonic flow-fields is one of the most important problem. Since, the flow inside SCRAM jet engine has high-enthalpy, an experimental facility is required to produce such high-enthalpy flow-field. In this study, a detonation-driven shock tunnel was built and was used to produce high-enthalpy flow. Further-more, SCRAM jet engine model equipped backward-facing step was installed at test section and flow-fields were visualized using color-schlieren technique and high speed video camera. The fuel was injected perpendicular to the flow of Mach number three behind backward-facing step. The height of the step, distance of injection and injection pressure were changed to investigate the effects of step on a mixing characteristic between air and fuel. The schlieren photograph and pressure histories show that the fuel was ignited behind the step.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.133-135
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• 2012

This study presents the prediction of NOx and mixing characteristics with several chemical reaction mechanisms of methane in EV burner of double cone. Experimental results are compared with numerical results for validation. Mixing characteristics are analyzed at monitoring points based on the modified unmixedness. The mixing characteristics were improved in a certain case, the lance injection case. In 1-step reaction case, inside of the cone, flame was formed and lots of NOx was generated because the fuel injected from the lance was overestimated. In 2-step reaction case, numerical results showed a good agreement with experimental results in a qualitative manner.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.49-55
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• 2007

The quality of chaotic mixing in three-dimensional micro channel flow has been numerically studied using Fractional-step method (FSM) and particle tracking techniques such as $Poincar{\acute{e}}$ section and Lyapunov exponents. The flow was driven by pressure distribution and the chaotic mixing was generated by applying alternating current to electrodes embedded on the bottom wall at a first half period and on the top wall at a second half period. The equations governing the velocity and concentration distributions were solved using FSM based on Finite Volume approach. Results showed that the mixing quality depended significantly on the modulation period. The modulation period for the best mixing performance was determined based on the mixing index for various initial conditions of concentration distribution. The optimal values of modulation period obtained by the particle tracking techniques were compared with those from the solution of concentration distribution equation using FSM and CFX software and the comparison showed their good match.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.616-623
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• 1996

This paper investigates the linear stability of reacting mixing layers with special emphasis on the existence of multiple unstable modes. The governing equations for laminar flows are from two-dimensional compressible boundary-layer equations. The chemistry is a finite rate single step irreversible reaction with Arrhenius kinetics. For the incompressible reacintg mixing layer with variable density. A necessary condition for instability has been derived. The condition requires that the angular momentum, not the vorticity, to have a maximum in the flow domain. New inflectional modes of instability are found to exist in the outer part of the mixing layer. For the compressible reacting mixing layer, supersonic unstable modes may exist in the abscence of a generalized inflection point. The outer modes at high Mach numbers in the reacting mixing layer are continuations of the inflectional modes of low Mach number flows. However, the generalized inflection point is less important at supersonic flows.

• Journal of the Korean Wood Science and Technology
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• v.26 no.2
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• pp.38-44
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• 1998

A new device that uses turbulent air for mixing wood fibers with thermoplastic fibers was designed and its mixing effectiveness was evaluated in wood fiber and polypropylene fiber composites. Composites made by the turbulent air mixing (TAM) process performed better than composites made by the conventional Rando-Webber forming or nonwoven web process with an additional needling step. Thus, the TAM process proved to be a simple and efficient method in mixing wood fibers with short thermoplastic fibers for the production of wood fiber and thermoplastic fiber composites.

• Environmental Engineering Research
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• v.21 no.4
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• pp.365-372
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• 2016

The effects of hydrodynamics and alum dose on particle growth were investigated by monitoring particle counts in a rapid mixing process. Experiments were performed to measure the particle growth and breakup under various conditions. The rapid mixing scheme consisted of the following operating parameters: Velocity gradient (G) ($200-300s^{-1}$), alum dose (10-50 mg/L) and mixing time (30-180 s). The Poisson regression model was applied to assess the effects of the doses and velocity gradient with mixing time. The mechanism for the growth and breakup of particles was elucidated. An increase in alum dose was found to accelerate the particle count reduction. The particle count at a G value of $200s^{-1}$ decreased more rapidly than those at $300s^{-1}$. The growth and breakup of larger particles were more clearly observed at higher alum doses. Variations of particles due to aggregation and breakup of micro-flocs in rapid mixing step were interactively affected by G, mixing time and alum dose. Micro-flocculation played an important role in a rapid mixing process.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.73.1-73.1
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• 2005

• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.17-22
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• 2010

The aim of this study is to research applicable possibility of DSI (Dry Sorbent Injection) technique in $SO_2$ removal process using lab-scale facility based on 500MW in capacity coal-fired thermal power plant operated by South Korea N. Power Co., Ltd. To increase the $SO_2$ removal efficiency, it is considered the mixing enhancement as different shapes called lobed-plate and stepplate tested ultimately for optimum shape. Also it tested to analysis $SO_2$ removal efficiency by numbers of injection holes. At experimental it showed the $SO_2$ removal efficiency is higher using mixing enhancement than not installed mixing enhancement and case on the step-plate was shown the most $SO_2$ removal efficiency. Also, $SO_2$ removal efficiency was higher recording which will increase the injection holes case on not installed mixing enhancement. But, the $SO_2$ removal efficiency was higher 4 injection holes case on installed mixing enhancement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.605-615
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• 1996

Laminar flows in which mixing and chemical reactions take place between parallel streams of reactive species are studied numerically. The governing equations for laminar flows are from two-dimensional compressible boundary-layer equations. The chemistry is a finite rate single step irreversible reaction with Arrhenius kinetics. Ignition, premixed flame, and diffusion flame regimes are found to exist in the laminar reacting mixing layer at high activation energy. At high Mach numbers, ignition occurs earlier due to the higher temperatures in the unburnt gas. In diffusion regimes, property variations affect the laminar profiles considerably and need to be included when there are large temperature differences. The maximum temperature of a laminar reacting mixing layer is almost linear with the adiabatic flame temperature at low heat release, but only weakly at high heat release.