• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.379-384
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• 2003

Coal-burning utilities are facing a major NOx control compliance challenge due to the heavy emission regulation. In response to this challenge, some applicative technologies to effectively reduce NOx are developed and applied in the pulverized coal power plants. One of these is low NOx burner(LNB) equipped with multi-staged air register. In this study, NOx emission rate and flame shapes are investigated with secondary and tertiary air flow conditions in air staged coal burner, and the optimal windows of flow conditions to minimize NOx emission rate are found out. The test conditions treated in this study are the flow rate, swirl direction and intensity and throat injection velocity of secondary and tertiary air.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.215-222
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• 2002

It has been well acknowledged that intake system plays great role in the performance of reciprocating engine. Well-designed intake system is expected to not only increase engine efficiency but also decrease engine emission, which is one of the most urgent issues in the automotive society. Thorough understanding of the flow in intake system helps great to design adequate intake system. Even though both experimental and numerical methods are used to study intake flow, numerical analysis is more widely used due to its merits in time and economy. Intake system of In-line 6-Cylinder CNG engine was chosen for the analysis ICEM CFD HEXA was used to create 3-D structured grid and FIRE code was used for the flow analysis in the intake system. Due to the complexity of the geometry standard ${\kappa}-{\varepsilon}$ turbulence model was applied. Numerical analysis was performed for various inlet and outlet boundary conditions under both steady and transient flow. Inlet mass flow rate and outlet pressure variation were changing parameters with respect to engine speed. Flow parameters, such as velocity, pressure and flow distribution, were evaluated to provide adequate data of this intake system.

• 한국농공학회지
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• 제45권1호
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• pp.45-54
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• 2003

The effects of binder content and silica sand content on the durability characteristics of lightweight polymer concretes are examined. As a result, the flame lingering times using unsaturated polyester resin and non-combustible polyester resin were 60∼120 and 0∼4 seconds respectively, and the combustion lengths were 9∼11 mm and 0∼3 mm, respectively. Thus it is believed that the lightweight polymer concrete was incombustible and the light weight polymer concrete in which non-combustible material was added was perfectly non-combustible. The percent of original mass of lightweight polymer concrete, according to the freezing-thawing experiment, was below 0.3 %, which was much less than that of cement concrete. The pluse velocity, for the case of the binder content 28 %, showed the minimum decreasing rate for the lightweight polymer concrete with silica sand content of 50 %. The higher the binder content, the greater the durability. That is much higher than other material and believed that the freezing-thawing was suppressed by a low absorption.

• 한국자동차공학회논문집
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• 제5권2호
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• pp.183-196
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• 1997

Gas flow field within the cylinder which is called a tumble flow is important factor in improving lean combustion stability. In this study, steady state flow tests were performed to quantify tumble ratio of flowfields generated by a tumble intensifying valve(TIV). In addition, velocity and fluctuation profiles in an intake port and flowfields in th cylinder were inspected using a hotwire anemometer and a laser light sheet method with various TIV configurations. These experimental results show that installated TIV has a great effect on flow field distribution in an intake port and test effects enhance a tumble flow in the cylinder.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2000년도 춘계 학술발표회 논문집
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• pp.209-214
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• 2000

The catalytic heat exchanger, which integrates two functions of heat generation and heat exchange into one equipment, was designed and its characteristics were investigated by experiments. The surface of the fin tube was deposited with Pd catalyst. The conversion of the mixture in the catalytic heat exchanger was more significantly affected by the inlet velocity of the mixture than by the inlet temperature and equivalence ratio of the mixture. It was found that the catalytic surface area of the fin tubes should be sufficiently increased to make the combustion intensity of the catalytic heat exchanger as high as possible. Results showed that the fin tubes, placed in the triangularly staggered form, should be adjusted so that the mixture flows uniformly over all the catalytic fin surfaces.

• 한국자동차공학회논문집
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• 제3권6호
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• pp.274-284
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• 1995

The effect of turbulence and ignition energy on flame kernel growth in mathanol-air mixtures has been studied in a constant volume vessel. Experiments were made under different turbulent intensity conditions, ignition energy and over a range of equivalence ratio. Characteristics of turbulent flow were grasped by measurments of gas pressure and visualization of flame propagation. Flow velocity was measured by use of hot wire anemometer. A comparison of the effect of turbulence on ignition probability and flame kernel volume variation ratio is also presented.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.36-40
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• 2004

일반적인 운용고도와 운항속도의 조건에서 스마트 무인기용 소형 가스터빈 엔진 연소기 내부의 유동 및 연소현상을 실험, 수치를 병행하여 연구하였다. 스마트 무인기의 비행모드에 따른 배압변화에 대한 이해를 위해 우선 무부하시 연소기 내부유동 및 연소현상을 수치해석으로 분석하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.309-317
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• 2012

Recent years have witnessed the use of micro shock tube in various engineering applications like micro combustion, micro propulsion, particle delivery systems etc. The flow characteristics occurring in the micro shock tube shows a considerable deviation from that of well established conventional macro shock tube due to very low Reynolds number and high Knudsen number effects. Also the diaphragm rupture process, which is considered to be instantaneous process in many of the conventional shock tubes, will be crucial for micro shock tubes in determining the near diaphragm flow field and shock formation. In the present study, an axi-symmetric CFD method has been applied to simulate the micro shock tube, with Maxwell's slip velocity and temperature jump boundary conditions. The effects of finite diaphragm rupture process on the flow field and the shock formation was investigated, in detail. The results show that the shock strength attenuates rapidly as it propagates through micro shock tubes.

• 한국추진공학회지
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• 제13권2호
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• pp.17-25
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• 2009

본 연구에서는 연소실의 축방향 압력과 속도변화를 고려한 비정상 내탄도 해석모델을 제안하고 이를 바탕으로 침식연소에 미치는 인자를 해석하였다. 개발 모델의 검증을 위하여 침식연소가 없는 경우와 침식연소가 있는 경우에 대하여 선행연구 결과와 비교하였으며 해석결과가 일치함을 확인하였다. 연소실 압력, 그레인 길이, 그레인 초기온도, 추진제 기화온도가 침식연소에 미치는 영향을 조사하였다.

• 대한기계학회논문집B
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• 제37권1호
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• pp.67-74
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• 2013

주류공기에 수직으로 분사되는 JICF 분사시스템은 연소실내에서 주류공기의 영향을 최소화하면서 미립화 및 연소성능을 향상시키기 위한 추진시스템의 연료분사 방식으로 넓은 적용범위를 가지고 있다. 하지만 JICF 분사시스템에서 산화제인 공기와 연료의 불충분한 혼합성능은 연소실 내에서의 불균일한 화염구조를 형성한다. 따라서 본 연구에서는 JICF 분사시스템의 램제트 연소기에서 연료와 공기의 부족한 혼합성능에 기인한 연소의 불균일한 화염구조를 실험적으로 확인하고, 연료 제트의 침투깊이, 분열점 등을 예측하기 위한 상관관계식을 유도함으로서 JICF 분사시스템에서 연소성능에 영향을 미치는 액체제트와 주류공기와의 분무 및 혼합특성을 파악하였다. 특히, 액체 제트의 침투깊이를 주류공기의 유동방향의 상류와 하류로 나누어 상관관계식을 유도하여 좀더 정확한 침투깊이의 예측이 가능하도록 하였다.