• Title/Summary/Keyword: tumble

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

  • Lee, Si-Hun;Kim, Myoung-Jin
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.6
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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.

Effects of Tumble Adaptor Configurations on the Intake Tumble Characterization (텀블-스월 변환장치 형상이 흡입텀블 특성화에 미치는 영향)

  • Kang, K.Y.;Lee, J.W.;Baek, J.H.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.5
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    • pp.66-73
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    • 1994
  • The configuration effects of a tumble adaptor which transforms tumble into swirl on the intake tumble characterization under steady flow condition have been investigated by LDV measurement The following parameters were involved to test their effects on tumble-swirl conversion characteristics ; the cylinder height and its bottom shape, measuring position in the swirl induction pipe, and the relative direction of the induction pipe. The short cylinder height and the flat bottom of the tumble adaptor were found effective for the generation of tumble in the cylinder, allowing higher tumble-swirl conversion efficiency.

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Steady Flow Characteristics of Four-Valve Cylinder Heads (실린더헤드 형상에 따른 정상유동 특성)

  • 배충식;정경석
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.5
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    • pp.197-205
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    • 1996
  • The flow characteristics of five different 4-valve cylinder heads were investigated in a steady flow rig using laser-Doppler velocimetry. The tumble flow of each head with pentroof combustion chamber was quantified by nondimensional tumble number using a tumble adaptor. The formation of tumbling vortex was examined in an optical single-cylinder engine which has windows for in-cylinder LDV measurements. Tumble vortex ratio was estimated from the tumble flow measurement. The four-valve cylinder heads with pent-roof combustion chamber showed the tumble vortex from the intake process, which was investigated in the steady flow test. The tumble adaptor which converts the tumble into swirl flow was found to be feasible in predicting the tumble flow in the real engine. The tumble strength in the steady flow test coincides with that in the real engine experiment within 15%. It was found that the steady flow test on the four-valve cylinder heads provides the tip for a better design of cylinder head.

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Analysis of Tumble Decay Mechanism through LDV Measurement in an Engine (LDV측정을 통한 엔진내 텀블감쇄 메카니즘 해석)

  • 강건용;이진욱;백제현
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.10
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    • pp.2773-2778
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    • 1994
  • Tumbling motion is very effective for turbulence enhancement during compression process in the cylinder of 4-valve engines. In this paper the tumble decay mechanism for different intake port configuration were measured using laser Doppler velocimetry. Analysis of the tumble decay mechanism was achieved by means of two non-dimensional parameters, defined as tumble eccentricity and shape factor in tumble velocity profile, in addition to the tumble moment.

CORRELATION STUDY OF THE MEASURED TUMBLE RATIOS USING THREE DIFFERENT METHODS: STEADY FLOW RIG; 2-DIMENSIONAL PIV; AND 3-DIMENSIONAL PTV WATER FLOW RIG

  • Kim, M.J.;Lee, S.H.;Kim, W.T.
    • International Journal of Automotive Technology
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    • v.7 no.4
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    • pp.441-448
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    • 2006
  • In-cylinder flows such as tumble and swirl play an important role on the engine combustion efficiencies and emission formations. The tumble flow, which is dominant in current high performance gasoline engines, is able to effect fuel consumptions and emissions under a partial load condition in addition to the volumetric efficiency under a wide open throttle condition. Therefore, it is important to optimize the tumble ratio of a gasoline engine for better fuel economy, lower emissions, and maximum volumetric efficiency. First step for optimizing a tumble ratio is to measure a tumble ratio accurately. For a tumble ratio measurement, many different methods have been developed and used such as steady flow rig, PIV, PTV, and LDV. However, it is not well known about the relations among the measured tumble ratios using different methods. The purpose of this research is to correlate the tumble ratios measured using three different methods and find out merits and demerits of each measurement method. In this research the tumble flow was measured, compared, and correlated using three different measurement methods at the same engine: steady flow rig; 2-dimensional PIV; and 3-dimensional PTV water flow rig.

Aspects of Children's Rough-and-Tumble Play during the Outdoor Play and Effects of Gender and Social Competence (바깥놀이에서 나타나는 유아의 거친 신체 놀이 양상 및 관련 변인 분석)

  • Kim, Young-Ah;Shin, Hae-Young
    • Korean Journal of Human Ecology
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    • v.16 no.5
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    • pp.945-955
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    • 2007
  • The purpose of this study was to explore the characteristics of the children's rough-and-tumble play, and investigate the differences in rough-and-tumble play according to children's gender and social competence. The subjects were 80 five to six year-old children. The children's behaviors during the outdoor play were observed by a modified version based on the Rough-and-Tumble Play Categories(Humphreys & Smith, 1987). Children's social competence was measured by using the Scale for the Social Competence of Kindergarten(Doh, 1994). The data were analyzed by descriptive statistics, t-test, and ANCOVA. The results were as follows: Firstly, about 25.6% of outdoor play types was rough-and-tumble play behaviors. Specifically, children's rough-and-tumble play was more 'chasing' behaviors than 'mock-fighting' behaviors. Secondly, boys involved in rough-and-tumble play more often than girls did. In general, boys participated more frequently in various rough-and-tumble play categories, whereas girls involved only in chasing behavior more often. Finally, controlled by sex, children with higher social competence participated more frequently in rough-and-tumble play, which showed statistical significance. In conclusion, children's rough-and-tumble play behaviors were related to the gender and the social competence.

A Study on the Flow Characteristics of the Intake Port and Cylinder Generated by a Tumble Intensifying Valve (텀블강화형 밸브에 의한 흡기포트 및 실린더내의 유동 특성에 관한 연구)

  • 이기형;이창식;정재우;전문수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.2
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    • pp.183-196
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    • 1997
  • Gas flow field within the cylinder which is called a tumble flow is important factor in improving lean combustion stability. In this study, steady state flow tests were performed to quantify tumble ratio of flowfields generated by a tumble intensifying valve(TIV). In addition, velocity and fluctuation profiles in an intake port and flowfields in th cylinder were inspected using a hotwire anemometer and a laser light sheet method with various TIV configurations. These experimental results show that installated TIV has a great effect on flow field distribution in an intake port and test effects enhance a tumble flow in the cylinder.

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The Effects of Tumble and Swirl Flows on the Flame Propagation in a 4-Valve Gasoline Engine (4-벨브 가솔린 엔진에서 텀블, 스월 유동이 화염전파에 미치는 영향)

  • Bae, Choong-Sik;Kang, Kern-Yong
    • 한국연소학회:학술대회논문집
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    • pp.153-162
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    • 1997
  • The effects of tumble and swirl flows on the flame propagation were investigated experimentally in a 4-valve optical gasoline engine. The tumble flow patterns, generated by various intake ports of different entry angle; $25^{\circ}$ , $20^{\circ}$ and $15^{\circ}$ , were characterized under motored conditions with laser Doppler velocirnetry. Inclined tumble(swirl) flows were induced by three different swirl control valves. The initial flame propagation was visualized by an ICCD camera and its image were analyzed to compare the enflamed area and displacement of initial flames. It was found that there is a correlation between the stronger tumble during induction and turbulence levels at the time of ignition resulting in faster flame development. Inclined tumble was proved to be more beneficial than the pure tumble for faster and stable combustion under lean mixture conditions, which was confirmed by faster propagating flame images.

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A Study on the Steady Flow Characteristics by PDA and Tumble Control Valve in Combustion Chamber (스월 및 연소실 형상에 의한 정상유동특성에 관한 연구)

  • Kim Dae-Yeol;Han Young-Chool;Park Bong-Kyu
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.4
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    • pp.74-82
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    • 2006
  • This paper describes the steady flow characteristics due to PDA and tumble control valve in combustion chamber. We also investigated the flow inclination angle defined as the inverse tangent of non-dimensional rig tumble(NRT) devided by non-dimensional rig swirl(NRS) to find dominant flow direction. So we adapted two different types of PDA valve(port deactivation valve) to strengthen a swirl flow. The in-cylinder swirl flow different tendency between with/without PDA valve. It might be thought to be affected by swirl flow. We could find that tumble ratio and swirl ratio is different by PDA valve. The comparison are taked account of the swirl, the tumble ratio comparison in same mass flow rate. As a result, PDA valve is better than tumble control valve both in steady flow condition and swirl, tumble ratio. The data from present study are available for design of engine as the basic data.

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

  • 조규백;전충환;장영준;강건용
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.5
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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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