• Title/Summary/Keyword: 텀블

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Characteristics of Tumble Flow in Cylinder of 4 Valve Gasoline Engine by Using Particle Tracking Method (입자 추적법을 이용한 4 밸브 가솔린 기관의 실린더 내 텀블 유동 특성)

  • Lee, Chang-sik;Chon, Mun-soo;Chung, Sung-hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.9
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    • pp.1178-1184
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    • 1999
  • The in-cylinder flow field of gasoline engine comprises unsteady compressible turbulent flows caused by the intake port, combustion chamber geometry and the change of the spatial shape. Thus the quantitative analysis of the in-cylinder bulk flow plays an important role in the improvement of engine performances and the reduction of exhaust emission. The influences of tumble intensifying valve (TIV) and swirl intensifying valve (SIV), and various intake-flow conditions are compared with the tumble ratio obtained by the measured results of the in-cylinder gas flow. In order to obtain the quantitative analysis of the in-cylinder gas flows of gasoline engine this investigation applied the particle tracking method to the analysis of gas flow characteristics. Various intake conditions such as tumble and swirl intensifying valve, the deactivated condition of one valve among two intake valves, and the other factors of gas flow are considered.

RAPID INITIAL DETUMBLING STRATEGY FOR MICOR/NANOSATELLITE WITH PITCH BIAS MOMENTUM SYSTEM (피치 바이어스 모멘텀 방식 초소형 위성의 초기 자세 획득 방안 연구)

  • Lee Byung-Hoon;Choi Jung-Won;Yun Mi-Yeon;Chang Young-Keun
    • Bulletin of the Korean Space Science Society
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    • 2006.04a
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    • pp.121-124
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    • 2006
  • B-dot logic is generally used for controlling the initial tip-off rate. However, it has the disadvantage of taking a relatively long time to control the initial tip-off rate. To solve this problem, this paper suggests a new detumbling control method to be able to adapt to micro/nanosatellite with the pitch bias momentum system. Proposed detumbling method was able to control the angular rate within 20 minutes which is a significant reduction compared to conventional methods.

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An Experimental Study for the Effect of Intake Port Flows on the Tumble Generation and Breakdown in a Motored Engine (모터링엔진의 흡기포트 유동변화에 따른 텀블생성 및 소멸에 관한 실험적 연구)

  • 강건용;이진욱;정석용;백제현
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.912-919
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    • 1994
  • The engine combustion is one of the most important processes affecting performance and emissions. One effective way to improve the engine combustion is to control the motion of the charge inside a cylinder by means of optimum induction system design, because the flame speed is mainly determined by the turbulence at compression(TDC) process in S.I. engine. It is believed that the tumble and swirl motion generated during intake stroke breaks down into small-scale turbulence in the compression stroke of the cycle. However, the exact nature of this relationship is not well known. This paper describes the tumble flow measurements inside the cylinder of a 4-valve S.I. engine using laser Doppler velocimetry(LDV) under motoring(non-firing) conditions. This is conducted on an optically assesed single cylinder research engine under motored conditions at an engine speed of 1000rpm. Three different cylinder head intake port configurations are studied to develop a better understanding the tumble flow generation, development, and breakdown mechanisms.

The Effects of Tumble and Swirl Flow on the Behavior of Liquid/Vapor Phases in a DI Gasoline Engine (직분식 엔진에서 실린더 내 연료의 액.기상 거동에 미치는 텀블과 스월의 영향)

  • 강정중;최동석;김덕줄
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.2
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    • pp.23-30
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    • 2002
  • This present study experimentally investigates the behavior of liquid and vapor phase of fuel mixtures with changing the in-cylinder air motion in an optically accessible engine. The conventional MPI/DOHC engine was modified to gasoline direct injection engine with swirl motion. The images of liquid and vapor phases were captured in the motoring operation condition using exciplex fluorescence method. Two dimensional spray fluorescence images of liquid and vapor phases were acquired to analyze spray behaviors and fuel distribution inside of cylinder respectively, In early injection timings $(BTDC\;270^{\circ},\;180^{\circ})$, tumble flow transported most of vapor phase to the lower region and the both sides of cylinder, so vapor phase didn't become uniform distribution up to the half of the compression stroke. In the case of swirl flow, the fuel mixture was confined near the swirl origin in upper region of cylinder. In late injection timings $(BTDC\;90^{\circ})$, tumble flow transported vapor phase to the intake valve and swirl flow to the exhaust valve.

A Numerical Study on the Characteristics of Tumble and Internal Flow According to Intake Port for Marine Engine (선박용 엔진의 흡기포트 형상에 따른 텀블 및 내부 유동 특성에 관한 수치적 연구)

  • Lee, Byoung-Hwa;Chang, Young-June;Jeon, Chung-Hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.4
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    • pp.498-505
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    • 2008
  • Many researches have been studied on in-cylinder flow as one of dominant effects for an engine combustion. The combustion phenomena of reciprocating engine is one of the most important processes affecting performance and emissions. One effective way to improve the engine combustion is to control the motion of the charge inside a cylinder by means of optimum induction system design. It is believed that the tumble and swirl motion generated during intake breaks down into small-scale turbulence in the compression stroke of the cycle. However, the exact nature of their relationship is not well known. To know this relationship definitely, this paper describes analytical results of the tumble motion, swirl motion, turbulence intensity, turbulence inside the cylinder of marine engine. 3-D computation has been performed by using STAR-CD solver and es-ice.

Numerical Analysis of Flow Characteristics in Swirl Chamber Type Diesel Engine (연락공 형상에 따른 와류실식 디젤기관의 유동 특성 수치해석)

  • Kwon Taeyun;Choi Gyeungho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.4
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    • pp.49-57
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    • 2005
  • In this study, in-cylinder flow of the swirl chamber type diesel engine numerically simulated by VECTIS code. The flow fields during the intake and compression process were also investigated in detail. Numerical results revealed that the generation and distortion of the swirling, tumbling vortices and those influences on turbulence kinetic energy by shape of the jet passage, angle and area. It was also found that flow characteristics were affected by inflow velocity that depends on change of the jet passage shape. Swirl ratio was increased according to decrease of jet passage area, and was affected by piston motion according to increase of jet passage angle. Tumbling vortices had the similar in various cases, but tumble ratio was increased with the inflow velocity. The generation of turbulence kinetic energy was considerably influenced by complex effects of swirling and tumbling vortices.

Analysis of in-cylinder steady flow for dual-intake-valve gasoline engine using single-frame particle tracking velocimetry (단일 프레임 입자 추적법을 이용한 흡입 2밸브 가솔린 기관의 실린더 내 정상 유동 해석)

  • Lee, Chang-Sik;Lee, Gi-Hyeong;Im, Gyeong-Su;Jeon, Mun-Su
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.5
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    • pp.650-658
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    • 1997
  • Analysis and control of intake charge motion such as swirl and tumble are very important factors in improving the gasoline engine performance. In this paper, single-frame PTV (particle tracking velocimetry) is used to investigate intake tumble patterns in a steady flow test rig of gasoline engine with dual-intake-valve and pent-roof combustion chamber. Intake tumble pattern is quantified in accordance with blockage ratio of TIV (tumble intensifying valve) with single- frame PTv.The view of the instantaneous 2-D velocity field gives a realistic understanding of in-cylinder flow field. Thus it is confirmed that PTV is a effective tool in engine design. In conventional port, two tumble structures appear clearly, and the larger one is observed under the exhaust valve side and the smaller is right below the intake valve side. The larger vorticity is observed in TIV port, thus it is concluded that TIV have an effect on intensified tumble motion in cylinder flow.

Diesel Engine Intake-Port Analysis Using Reverse-Engineering Technique (리버스 엔지니어링을 통한 디젤엔진 흡기포트의 분석)

  • Park, Sung-Young;Kim, Yong-Tae
    • Proceedings of the KAIS Fall Conference
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    • 2012.05b
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    • pp.674-676
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    • 2012
  • 본 논문에서는 3차원 설계데이터가 부재한 디젤엔진 실린더 헤드의 흡기포트 데이터를 확보하기 위하여 리버스 엔지니어링 기법을 적용하였다. 획득된 해석 모델을 이용하여 디젤엔진 흡기포트에 대한 유동해석을 수행하였으며, 텀블 유동과 스월유동의 존재를 해석 결과로서 확인할 수 있었다. 이러한 기법의 적용은 향후 3차원 설계데이터가 부재한 엔진이나 경쟁엔진의 분석에 유용하게 적용될 수 있을 것으로 판단된다.

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A Study on In-Cylinder Flow Motion of Swirl and Tumble in a 2- Valve Type Gasoline Engine (2밸브 가솔린엔진의 실린더내 스월 및 텀블유동연구)

  • Eom, Jong-Ho;Jeong, Dong-Su;Lee, Jin-Uk
    • 연구논문집
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    • s.23
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    • pp.63-71
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    • 1993
  • To improve flow in-cylinder flow in a 2-valve gasoline engine, various geometries of combustion chambers are modified. Air flow rate, swirl and tumble flow are measured and analyzed by swirl impulse meter and LDV in a steady state flow measuring rig. The results of LDV experiment are compared with the data of swirl impulse meter.

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Numerical Investigation of the Effect of IR Heating on Drying Mechanism in a Tumble Dryer (열복사를 적용한 드럼 건조기의 건조 메커니즘 분석 및 성능 예측에 관한 연구)

  • Choi, Chul-Jin;Jang, Jung-Hyun;Kim, Chong-Min;Kim, Man-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.3
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    • pp.219-228
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    • 2010
  • A two-dimensional mathematical model was developed to predict the temperature and moisture-content profiles of a tumble dryer during infrared drying. The model is based on the movements of liquid water and moisture in the object and on the fluid and heat transfer in the drying air. The model was solved by the finite volume analysis for the fluid, temperature, and radiation intensity fields. After deriving the governing equations and developing the two-dimensional tumble dryer models, numerical investigations were carried out to examine the effects of various parameters such as the heater temperature and the heating patterns on the drying mechanism of the tumble dryer. All the results show that the drying time can be reduced by using the IR heater.