• 대한기계학회논문집B
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• 제33권11호
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• pp.849-857
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• 2009

The experimental study was performed to investigate the effects of partial premixing, varying the equivalence ratio, mixing degree, swirl intensity, mixing length on the characteristics of flame structure and NOx emission. Experiments were conducted in a dump combustor at 1 bar using methane as fuel. Inlet air temperature was 570K. OH chemiluminescence images were acquired with an ICCD camera. As a result of the experimental investigation of characteristics of flame and NOx emission in partial premixed combustor, we can conclude the results as below. With the increase of swirl number, The flame length decreases and the flame width increases and it helps flame stabilization. It means that lean flammability limit is extended. With the increase of mixing of fuel-air length ratio, Flame goes to be stabilized and NOx emission and $OH^{\ast}$ intensity decrease. Through the comparison of preceding results, It is possible that the exhausted NOx emission from a gas turbine combustor will be able to predict through the $OH^{\ast}$ intensity.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.70-75
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• 2012

본 연구는 End-Burning 하이브리드 로켓 연소에서 연료직경과 인젝터 형상 변화, 인젝터 각도 변화를 통한 스월강도 변화에 따른 연소특성의 변화을 알아보기 위해 수행하였다. 연료직경이 커지면 연료의 연소량이 증가하고, 인젝터 직경이 커질수록 후퇴율이 낮아졌다. 그리고 본 연구의 End-Burning 연소기는 고체연료의 연소율에 미치는 영향이 산화제 유동의 Impinging 효과 보다는 Swirl 효과가 더 큼을 확인했다. 스월상수를 적용한 후퇴율식을 도출하여, 스월상수가 서로 다른 경우들에 대한 후퇴율 관계식을 하나의 식으로 표현할 수 있었다.

• 대한기계학회논문집
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• 제7권4호
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• pp.410-416
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• 1983

This study presents the combustion characteristics and flame structure of annular swirling flow when there were changes the equivalence ratio and swirl number of swirling jet of fuelair mixture. The conclusions of this study are as follows; During the investigations in which the change of equivalence ratio and swirl number were studied, three basic shapes of flame were observed in this study. Visible flame lengths of swirling jet results in the decrease with increasing of swirl number and air-fuel ratio of mixture. Radial distribution of flame temperature with strong swirl is higher than that of weak swirl at the same equivalence ratio of mixture. The angle of spread of the annular jet increases with the increase of swirl number. When the swirl intensity is increased in a jet, the decay of concentration of carbon dioxide is decreased with the distance from nozzle exit of burner.

• 한국항공우주학회지
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• 제33권7호
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• pp.70-75
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• 2005

본 연구에서는 스월 연소기에서 연료스월유동이 NOx 배출특성에 미치는 영향을 실험적으로 조사하였다. 공기와 연료스월각을 변화시키기 위해 환형베인을 사용하였고 베인각의 변화에 따라 혼합공정을 변화시켰다. 공기스월이 강한 조건에서 연료 Counter-swirl의 경우, 비연소장에서 큰 난류강도의 특성을 나타내고 상대적으로 고주파 영역까지 높은 에너지를 가지고 있으며, 고온 영역이 좁게 나타났다. 이러한 연료 counter-swirl 영향으로 저NOx 배출특성이 나타났으며, NOx 저감 기구가 논의되었다.

• Journal of Mechanical Science and Technology
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• 제18권10호
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• pp.1819-1828
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• 2004

The purpose of this paper is to investigate the effects of slits and swirl vanes on the turbulence augmentation in the flow fields of a gun-type gas burner using an X-type hot-wire probe. The gun-type gas burner adopted in this study is composed of eight slits and swirl vanes located on the surface of an inclined baffle plate. Experiment was carried out at a flow rate of 450 ι/min in burner model installed in the test section of subsonic wind tunnel. Swirl vanes playa role diffusing main flow more remarkably toward the radial direction than axial one, but slits show a reverse feature. Consequently, both slits and swirl vanes remarkably increase turbulence intensity in the whole range of a gun-type gas burner with a cone-type baffle plate.

• Journal of Advanced Marine Engineering and Technology
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• 제29권3호
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• pp.260-274
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• 2005

An experimental investigation was performed to study the characteristics of turbulent swirling flow in the cylindrical annuli. The swirl angle measurements were performed by flow visualization technique using smoke and dye liquid. By using the particle image velocimetry method. this study has found the time-mean velocity distribution and turbulent intensity with swirl for Re=20,000. 30.000. 50.000. and 70,000 along longitudinal sections. The results appear to be physically reasonable. Other experimental study was performed to investigate heat transfer characteristics of turbulent swirling air flow in axisymmetric annuli. The static pressure. the local air flow temperature, and the wall temperature with decaying swirl were measured by using thermocouples and the friction factor and the local Nusselt number were calculated for Re=30,000. 50,000 and 70000. The local Nusselt number was compared with that obtained from the Dittus-Boelter equation with swirl and without swirl, respectively. The results showed that the swirl enhances the heat transfer at the inlet and the outlet of the test tube.

• 한국추진공학회지
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• 제23권1호
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• pp.1-8
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• 2019

스월/전단 동축형 인젝터를 통해 형성된 기체메탄-기체산소 확산화염의 동역학적 거동 및 구조분석을 위해 다양한 추진제 분사조건에 따른 연소실험이 수행되었다. 연구결과, 자발광 기법을 통해 가시화된 확산화염의 $OH^*$ 방사강도는 추진제 공급유량 및 운동량 플럭스 비 증가에 따라 높은 값을 나타내고 있으며, 스월을 가지는 화염은 그렇지 않은 것에 비해 더 우수한 반응성을 보였다.

• 대한기계학회논문집B
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• 제25권7호
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• pp.997-1004
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• 2001

Burner of Flat Flame type expects the uniform flame distribution and NOx reduction. The characteristics of Flat Flame Burner become different according to swirl number in the burner throat. Experiments were focused on swirl effect by four types of swirler with different swirl numbers (0, 0.26, 0.6 and 1.24). It shows many different flow patterns according to swirl number using PIV(Particle Image Velocimetry) method. The flow of burner with swirler is recirculated by pressure difference between its center and outside. Recirculated air makes stable in flame, and reduced pollutant gas. In case of swirl number 0, main flow passes through axial direction. As swirl number increased, The backward flow develops in the center part of burner and Flow gas recirculates. This is caused by radial flow momentum becomes larger than axial flow by swirled air and the pressure at center drops against surrounding. As swirl number increases, the radial and axial velocity was confirmed to be larger than low swirl numbers. And turbulence intensity have similar pattern. The CTRZ(Central Toroidal Recirculation Zone) is shown evidently when y/D=1 and S=1.24. The boundary-layer between main flow and recirculated flow is shown that the width is seen to be decreased as swirl number increased.

• 대한기계학회논문집B
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• 제20권1호
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• pp.244-254
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• 1996

Flow velocity was measured by, use of hot wire anemometer. Turbulence intensity was in proportion to mean flow velocity regardless of swirl velocity. And integral length scale has proportional relation with swirl velocity regardless of measurement position. Turbulent burning speed during flame propagation which was determined by flame photograph and gas pressure of combustion chamber was increased with the lapse of time from spark and was decreased a little at later combustion period. Because of combustion promotion effect, turbulent burning speed was increased according to increase of turbulence intensity. Burning speed ratio i.e. ratio of turbulent burning speed ($S_BT$) to laminar burning speed ($S_BL$) was found out by use of turbulence intensity u' and integral length scale $l_x$ , $\delta_L$ is width of preheat zone in laminar flame.

• 한국자동차공학회논문집
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• 제2권2호
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• pp.12-23
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• 1994

In order to investigate the effect of turbulent intensity on combustion characteristics, new flame factor model was developed. The principal study is the evaluation of interaction of swirl, tumble and unstrutural component of flow characteristics and correlation between turbulent intensity and flame factor. Computational and experimental study has been, performed such as quasi-dimensional cycle simulation, three dimensional flow analysis, engine performance test and diagnostic simulation. From these studies, it was found that flame factor was a function of engine speed and turbulent intensity.