• Journal of Advanced Marine Engineering and Technology
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• 제19권3호
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• pp.9-23
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• 1995

To analyze the spray and flame in D.I. diesel engine, the visualizing methods by schlieren photograph and diffused background illumination photograph with high speed camera are applied to optically accessible D.I.diesel engine. Wcaporating spray, spray droplets and brightness flame are taken with high speed camera by visuallizing method in accordance with various suction air temperature and injection time. The spray and flame image on the film was analyzed by image analyzer. The optically accessible D.I. diesel engine had the similar pressure characteristic to the real D.I. diesel engine. Experimental results showed that shadow areas of the evaporating spray were extended at higher suction air temperature, spray droplets had a max. Penetration length and their penetrating patterns were dependent on the surrounding gas temperature, and flame size after ignition was largely governed by the evaporated fuel quantity at ignition point and by the surrounding gas condition due to piston motion.

• 한국가시화정보학회지
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• 제11권1호
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• pp.22-27
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• 2013

An investigation into the influence of ultrasonic standing wave on the structural behavior of propane/air premixed flame has been made to get a clue to the combustion reaction acceleration and combustion instability. Visualization technique utilizing the Schlieren photography was employed for the observation of structural variation of the flame reaction zone. Evolutionary characteristics of the flame front were caught by the high-speed Schlieren image, through which local flame velocity of the moving front were analyzed in detail.

• 한국가시화정보학회지
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• 제9권3호
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• pp.30-37
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• 2011

The thrust vectoring concept has been used for use in new advanced supersonic aircraft. This study presents the performance characteristics of the thrust vectoring nozzle by visualizing the shock behaviors with Schlieren method. The scaled models were designed and manufactured to see the shock behaviors of the various airflow condition. Also we executed experimental tests to see the geometrical effects of the thrust vector nozzle by changing pitch angle and length of pitch flaps. From this study we could understand the supersonic flow characteristics of the thrust vector nozzle. The total thrust of thrust vector nozzle is diminished by increasing the flap angle. But there is an optimum flap length ratio for attaining the highest thrust level and proper pitch effect.

• 한국분무공학회지
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• 제5권4호
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• pp.33-39
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• 2000

The behavior of the 2-stage spray was studied by using the schlieren method with the high pressure common-rail injection system. The spray injected 2 times with the interval of $0.3ms{\sim}1.5ms$ between the 1st and the 2nd spray in a modeled combustion chamber of constant volume bomb. In this case, the quantity of injected fuel of 1st and 2nd also changed. The schlieren photograph shows that the 2nd spray goes further away than the 1st spray when the quantity of the 1st spray is less than that of the 2nd spray. The dispersion of the vapour to the combustion chamber is not affect in a 10% of 1st spray quantity. When the 1st spray quantity is more than the 2nd spray, the vapour scattering of spray is good.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1691-1698
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• 2001

In recent years, significant progress has been made in modeling turbulence behavior in plasma and its effect on transport. It has also been made in diagnostics for turbulence measurement; however, there is still a large gap between theoretical model and experimental measurements. Visualization of turbulence can improve the connection to theory and validation of the theoretical model. One method to visualize the flow structures in plasma is a laser Schlieren imaging technique. We have recently applied this technique and investigated the characteristics of a highly underexpanded pulsed plasma jet originating from an electrothermal capillary source. Measurements include temporally resolved laser Schlieren imaging of a precursor blast wave. Analysis on the trajectory of the precursor blast wave shows that it does not follow the scaling expected for a strong shock resulting from the instantaneous deposition of energy at a point. However, the shock velocity does scale as the square root of the deposited energy, in accordance with the point deposition approximation.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.575-578
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• 2011

추련편향 개념은 최신의 초음속 전투기에 적용되어 사용되고 있다. 본 연구는 추력편향노즐의 성능특성을 쉴리렌기법을 이용한 충격파 가시화를 통하여 제시한다. 피치 각 변화와 피치플랩길이 변화라는 추력편향노즐의 기하학적인 특성에 따른 실험평가를 수행하고, 이러한 연구를 통하여 추력편향노즐의 초음속 유동특성을 분석하였다. 추력편향노즐의 총 추력은 편향각도가 증가함에 따라 감소되며, 추력손실이 가장 적으면서 적절한 편향 효과를 가지는 최적의 플랩 길이비가 존재한다.

• 한국해양공학회지
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• 제10권4호
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• pp.128-140
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• 1996

To analyze a formation process of the soots in spray flame in the combustion chamber, an optically accessible DI Diesel engine was used for visualization. The images of the flames and soots were visualiaed with high speed camera by Schlieren method and Light extinction method. The spray flame and soot images on the films were analyzed at the various engine operating conditions. Soot distributed widely in spray flame and its concentration was about $100g/m^3$ at the position close by nozzle tip of spray flame region, however it decreased below $20g/m^3$ at the corner of combustion chamber due to soot oxidation.

• 한국분무공학회지
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• 제25권3호
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• pp.111-118
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• 2020

This paper describes the effect of DME, biodiesel blended fuels on the macroscopic spray characteristics in a high pressure diesel injection system using Background Oriented Schlieren (BOS) method. The BOS method for visualization of impingement evaporation sprays to analyze macroscopic spray properties and evolutionary processes. In this work, the blending ratio of DME in the blended fuel are 0, 50, 100% by weight ratio. In order to investigate the macroscopic impinged spray characteristics under the various injection parameters and blending ratio. In this work, a mini-sac type single-hole nozzle injector with nozzle hole was length 0.7 mm and diameter of 0.3 mm was used. According to the result, the spray area of the collision wall increased as the DME mixing ratio increased, and the evolutionary pattern showed a stepwise increase due to the collision effect of the wall. Also, results of impinged spray area were increased according to increasing injection pressure.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1829-1834
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• 2001

The choking of dual subsonic streams flowing through a convergent duct in contact has been investigated experimentally and theoretically. The experiment was conducted by using blow-down wind tunnel. The condition, when the dual stream flow chocking (compound choking) occurs at the nozzle exit, was explained by one-dimensional analysis of compound sound wave propagation. The experimental results for the condition of compound choking were compared with the prediction from theoretical analysis, and the schlieren optical method using the spark light source has been used to visualize the flowfield.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.279-280
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• 2006

In the present study the flow fields around pitching foils have been visualized by using a Schlieren method with a high speed camera in a wind tunnel at low Reynolds number regions. It has been observed that small vortices are shed discretely from the leading and trailing edge and that they stand in line on the integrated streakline of separation shear layer. By counting vortices in the VTR frames it was clarified that the number of vortex shedding from the leading and trailing edge during one pitching cycle strongly depends on the non-dimensional pitching rate.