• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.6
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• pp.9-17
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• 2007

This experimental study has been conducted to investigate the effect of the recirculation zone on the multi-slot film cooling in the ramjet combustor. The recirculation zone which is generated by the protrusion tip on the entrance of the coolant flow path affects on the first slot. Velocity fields, dimensionless temperature fields and adiabatic film cooling effectiveness on the downstream wall of the slot exit are measured. The results show that the film cooling performance is rapidly decreased after the slot exit by shear layer and high turbulence intensity between separated flows and coolant flows.

• Journal of the KSME
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• v.34 no.9
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• pp.705-710
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• 1994

열.유체유동 중 난류에 대한 유동현상은 매우 광범위한 영역에서 나타나기 때문에 그 응용성이 매우 크게 작용되어 상업용 설비, 항공기, 자동차, 연소기 및 각종 스포츠 등에 이르기까지 넓게 적용되고 있다. 본 계측법은 특히 기하학적 형상에 좌우되지 않는 범용데이터 처리와 결부시켜 이용하는 것으로 최근 컴퓨터의 보급이 활발히 정착됨에 따라 보다 정확한 방법으로 난류의 정량적인 자료와 정성적인 난류구조를 계측하기 위하여 컴퓨터와 온라인으로 연결한 열선한 열 선유속계의출력을 통계해석에 의해 분석하는 방법이 시도되고 있는 것이다. 끝으로 이 글에서 언급한 삼축 열선 프로브는 프로브의 제작에 대한 고도의 기술과 프로브의 겁사체적을 되도록 작게 해야 하는 과제를 안고 있으며, 이러한 문제들은 제작기술의 발달로 점차 해결되고 있으며 적용대상이 크기 때문에 앞으로 많이 이용 될 것으로 기대되는 바이다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2150-2158
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• 1992

This study was carried out to investigate the flow structure and mixing process of a cross mixing flow formed by two round jets with respect to the ratio of mass flow rate. This flow configuration is of great practical relevance in a variety of combustion systems, and the flow behaviour of a cross jet defends critically on the ratio of mass flow rate and the cross angle. The mass flow rate ratios of two different jets were controlled as 1.0, 0.8, 0.6, and 0.4, and the crossing angle of two round jets was fixed at 45 degree. The velocities issuing from jet nozzle with an exit diameter of 20mm were adjusted to 40m/s, 32m/s, 24m/s, and 16m/s, and the measurements have been conducted in the streamwise range of $1.1X_0$to $2.5X_0$ by an on-line measurement system consisted of a constant temperature type two channel hot-wire anemometry connected to a computer analyzing system. The original air flow was generated by a subsonic wind tunnel with reliable stabilities and uniform flows in the test section. For the analysis of the cross mixing flow structure in the downstream region after the cross point, the mean velocity profiles, the resultant velocity contours, and the three-dimensional profiles depending upon the mass flow rate ratio have been concentrately studied.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.1
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• pp.43-48
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• 1997

The present study is aimed to investigate experimentally on the hydrodynamic behaviours of air ~ pulverized coal flow in rectangular combustor with cavity. Mean velocity, density and tur¬bulent properties of pulverized coal in rectangular entrained flow combustor were measured by PDA. Experimental results show that the flow reattachment point at the lower plane in the com¬buster chamber has been developed near X/D= 15. The similarities at each section are found after the flow reattachment point. The maximum values of turbulent intensity and Reynolds shear stress have been shown near Y/D=6, which is higher than centerline. The maximum density of the pulverized coal sited in the range ofY/D=6~8.

• Journal of Energy Engineering
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• v.4 no.1
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• pp.115-125
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• 1995

본“천연가스 다단연소기술 연구”는, 공업적으로 널리 쓰이는 선회확산 방식으로 천연가스를 연소시킬 때 그 연소 특성과 발생되는 환경오염물질인 일산화탄소(CO)와 질소산화물(NOX)의 저감에 대한 연구로서, 천연가스의 난류확산화염과 선회확산화염의 유동장, 온도장, 농도장을 실험과 수치해석을 통하여 분석하여 각각 연소방식의 화염구조와 특성을 규명하고 해석하였다. 그리고 그 결과를 토대로하여 다단확산 연소실험 장치를 제작 다단확산연소의 중요한 인자인 1차당량비, 2차공기주입위치, 유속, 선회도 등을 변화시켜 질소산화물 저감과 높은 연소효율을 얻을 수 있는 최적의 연소조건을 찾아 내었다. 본고에서는 실험부분만을 간추려 발표하고 수치해석 부분은 다음 기회로 미루고자 한다.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1084-1093
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• 2010

Large eddy simulation of turbulent premixed flame stabilized by the bluff body is performed by using sub-grid scale combustion model based on the G-equation describing the flame front propagation. The basic idea of LES modeling is to evaluate the filtered-front speed, which should be enhanced in the grid scale by the scale fluctuations. The dynamic subgrid scale models newly introduced into the G-equation are validated by the premixed combustion flow behind the triangle flame holder. The calculated results can predict the velocity and temperature of the combustion flow in good agreement with the experiment data.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.303-308
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• 2006

This paper describes numerical efforts to investigate combustion characteristics of HyShot scramjet engine. The corresponding altitude, angle of attack, and equivalence ratio are 28 km, $0^{\circ}$, and 0.426 respectively. $H_2$ and OH mass fraction show that the upstream recirculation zone of injector has flame-holding effects and main combustion begins at 15 cm downstream from cowl. Two-dimensional simulation reasonably predicts combustor inner pressure and also reveals periodic combustion characteristics of HyShot scramjet engine.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.437-441
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• 2010

LES results of turbulent premixed combustion flows are introduced by using the dynamic sub-grid scale model based on G-equation describing the flame front propagation. The turbulent premixed combustion flows around bluff body and over backward facing step are analyzed to validate present formation. LES of swirling partially premixed combustion flame is also performed to conform the predictive capabilities of LES model and to prompt our understanding for the combustion flows over double cone swirl burner combustor by using CFD-ACE+ commercial code.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.2
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• pp.86-94
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• 1987

In order to examine the flow motion in a combustion chamber of a motored diesel engine, the variation of instantaneous are velocity at a fixed point in combustion chamber was measured by the constant temperature hot wire anemometer, varing engine speed, shroud shape and shroud position. The results are summerized as follows: 1. The variation of air velocity in a combustion chamber is closely related with the valve timing and piston velocity. 2. The air velocity in the cylinder at suction stroke is being increased and maximized at 60$^{\circ}$ ABDC in compression stroke and then decreased at the e.v.o. in expansion stroke. 3. The mean velocity using shroud valve was less than no shroud valve. However the turbulent intensity using shroud valve was larger than no shroud valve. 4. The turbulent intensity with 90$^{\circ}$shroud valve was larger than that of 120$^{\circ}$shroud valve, and 90$^{\circ}$shroud valve at 180$^{\circ}$shroud position had the largest turbulent intensity.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.23 no.2
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• pp.40-40
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• 1987

In order to examine the flow motion in a combustion chamber of a motored diesel engine, the variation of instantaneous are velocity at a fixed point in combustion chamber was measured by the constant temperature hot wire anemometer, varing engine speed, shroud shape and shroud position. The results are summerized as follows: 1. The variation of air velocity in a combustion chamber is closely related with the valve timing and piston velocity. 2. The air velocity in the cylinder at suction stroke is being increased and maximized at 60° ABDC in compression stroke and then decreased at the e.v.o. in expansion stroke. 3. The mean velocity using shroud valve was less than no shroud valve. However the turbulent intensity using shroud valve was larger than no shroud valve. 4. The turbulent intensity with 90°shroud valve was larger than that of 120°shroud valve, and 90°shroud valve at 180°shroud position had the largest turbulent intensity.