• 제목/요약/키워드: 텀블

검색결과 84건 처리시간 0.024초

PIV에 의한 4밸브 가솔린기관의 흡기포트 형상에 따른 정상유동 해석 (Characteristics of In-cylinder Steady Flow using PIV for Different Intake Port Geometries in a 4-valve Gasoline Engine)

  • 조규백;전충환;장영준;강건용
    • 한국자동차공학회논문집
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    • 제5권5호
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    • pp.188-196
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    • 1997
  • Many researchers have developed the measurement technique of in-cylinder flow characteristics and found the effect of intake port geometries on engine performance. The flow characteristics of four-valve cylinder head were examined in a steady flow rig for different intake ports. Tumble intensity of intake configurations with different entry angles were quantified with a tumble meter. The velocity and angular momentum distributions in the tumble adaptor were measured under steady conditions with PIV(Particle Image Velocimetry). We have obtained the results that flow structure becomes complicated by valve interference at low valve lift. As the valve interferences were reducing and the flow pattern changed to large vortex structure with tumble direction, intake ports with different entry angles have different tumble centers. Tumble eccentricity of intake port with low entry angle was large, so that the port had relatively much angular momentum compared to others which was expected to improve combustion performance.

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엔진내부 텀블 유동 형성에 대한 수치해석적 연구 (Numerical Study on the Formation of Tumble Motion in Engine Cylinder)

  • 이병서;이준식;유정열
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.2233-2238
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    • 2003
  • It is well known that organized vortex rotations swirl and tumble greatly affect the mixing, the combustion and heat transfer processes in engine cylinder. We have developed 3 dimensional numerical simulation codes whose predictions make good agreement with the experimental data. Large eddy simulation based on Smagorinsky subgrid scale model was adopted to describe the turbulence of in-cylinder flows. The tumble motions generated by different inclination angles between valve-port and cylinder head have been calculated. The results show that the angles between direction of induced flow and cylinder walls which the flow collides with play a great role in the formation and generation of tumble motions. Therefore, it is inferred that seat angle and inclination angle are important factors of engine design. In addition, the numerical results of different engine speed -1000 rpm and 3000 rpm are very similar in the flow structure.

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밸브위치에 따른 4밸브 엔진 연소실 내부의 스월비와 텀블비의 거동 (The behavior of swirl and tumble ratio in the combustion chamber of 4-valve engine with valve positions)

  • 김성준;이천식;전봉준;이용일
    • 산업기술연구
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    • 제19권
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    • pp.51-57
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    • 1999
  • This research has an object to find out how the position of inlet valve influence swirling and tumbling of turbulence inside the combustion chamber of 4 valve engine. The computational analysis of three dimensional complicated turbulence flow in the cylinder is done by the KIVA-3V program to carry out this object. One use 6 valve positions with the bowl type of piston cavity. The swirl ration and the tumbling ratio of flow filed are evaluated quantitatively to find out how each valve position influence flow phenomena in the combustion chamber during the intake and compression processes.

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수동변속기 차량의 발진 스텀블 해석 (Analysis of Stumble of Manual Transmission Vehicle during Standing Start)

  • 강재훈;김택수;박경석;한태식
    • 한국자동차공학회논문집
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    • 제17권3호
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    • pp.102-109
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    • 2009
  • The stumble (abrupt and big acceleration decrease) occurring in manual transmission vehicle while standing start is analyzed by simulation model. This model was verified by comparing to test results. Mechanism of the stumble is clarified by analyzing simulation results and the key mechanism of the stumble is angular vibration of powertrain including wheel and tires. As a result, several method that can reduce the stumble is proposed by carrying out parametric study, increasing low end torque of engine, increase gear ratio etc.

SCV형상별 경사텀블유동의 난류증가 특성 해석 (Turbulence Enhancement Characteristics Analysis of Inclined-Tumbles for Various SCV Configurations)

  • 이진욱;강건용;최승환;박승철
    • 한국자동차공학회논문집
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    • 제6권6호
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    • pp.234-242
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    • 1998
  • It has been demonstrated that the in-cylinder turbulence is enhanced by inclined swirl with a SCV(swirl control valve). The inclined-tumble flow measurement and analysis were performed for various types of intake systems that generated several different combinations of swirl ratio and tumble ratio in the cylinder. Experiments were conducted in a 4-valve optically accessed transparent research engine using a backward-scatter LDV mode under motoring condition at 1,000rpm. The influence of swirl/tumble levels on the characteristics of turbulence was analysed. This study presents experimental results of the inclined-tumble flow structure, including the flow motion phenomena, angular momentum and turbulence intensity.

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피치 바이어스 모멘텀 방식을 사용하는 초소형 위성의 초기 자세획득 방안 연구 (Rapid Initial Detumbling Strategy for Micro/Nanosatellite with Pitch Bias Momentum System)

  • 이병훈;최정원;장영근;윤미연
    • 한국항공우주학회지
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    • 제34권5호
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    • pp.65-73
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    • 2006
  • 위성이 발사체로부터 분리될 때 초기 각속도가 발생한다. B-dot 로직은 일반적으로 위성의 초기각속도 제어에 사용되나, 상대적으로 제어시간이 많이 소요된다는 단점이 있다. 이런 문제를 해결하기 위해 본 논문에서는 피치 바이어스 모멘텀 방식을 사용하는 초소형 위성에 적용 가능한 디텀블링(detumbling) 방식을 새롭게 제안하였다. 제안된 디텀블링 방식은 제어시간이 약 20분 이내로 기존의 방식에 비해 상당한 시간을 줄일 수 있다. 본 논문에서 제안한 디텀블링 방식을 사용할 경우 기존의 모멘텀 휠 초기구동 방식을 사용할 수 없다. 따라서 휠의 속도를 안정적으로 공칭 속도까지 증가시키는 방식을 제안하고 시뮬레이션을 통해 비교, 검증하였다. 시뮬레이션 결과 기존의 방식과 비교했을 때 제어시간을 단축할 수 있었으며 휠의 공칭 속도와 3축 안정화를 이룰 수 있었다.

엔진대상시험을 통한 텀블측정방식의 상관성 및 유의성에 관한 연구 (Correlations among Different Tumble Measuring Methods and Significance of Tumble Ratios from Steady Flow Rig on SI Engine Combustion)

  • 이시훈;김명진
    • 한국자동차공학회논문집
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    • 제14권6호
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    • pp.43-49
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    • 2006
  • Optimizing in-cylinder flow such as tumble or swirl is one of the key factors to develop better internal combustion engines. Especially, the tumble, which is more dominant flow in current high performance gasoline engines, has significant effects on the fuel consumptions and exhaust emissions under part load conditions. The first step for the tumble optimization is to find an accurate but cost-effective way to measure the tumble ratio. From this point of view, tumble ratios from three different measuring methods were compared and correlated in this research. Steady flow rig, water rig, and PIV were utilized for that purpose. Engine dynamometer test was also performed to find out the effect of the tumble. The results show that the tumble ratios from those methods are well correlated and that the steady flow rig is the effective method to measure the tumble despite its limitations.