• Title/Summary/Keyword: Flow direction

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Flow Direction Characteristics in the Vicinity of the Spark Plug in an S. I. Engine

  • Han, Sung-Bin;Chang, Yong-Hoon;Chung, Yon-Jong
    • Journal of Mechanical Science and Technology
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    • v.14 no.8
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    • pp.891-899
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    • 2000
  • The flame speed may be decomposed into the burning speed and the flame transport speed. The flame transport speed is affected considerably by the flow direction, variation rate of flow direction, and flow speed in the combustion chamber. Especially, the flow direction and the variation rate of flow direction at the spark plug location during the ignition period have an important effect on the ignition process and the early flame propagation process. We measured the flow direction component and the variation rate of flow direction with a hot wire probe at the spark plug location. It was shown that the representative flow direction of ignition period is the right-vertical direction of crank shaft and it was used to investigate the variation rate of flow direction.

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Analysis of Variation for Drainage Structure with Flow Direction Methods Based on DEM

  • Meiyan, Feng;Kahhoong, Kok;Kim, Joo-Cheol;Kwansue, Jung
    • Proceedings of the Korea Water Resources Association Conference
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    • 2018.05a
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    • pp.325-325
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    • 2018
  • The main purpose of this study is to suggest the more reliable flow direction methods within the framework of DEM by investigating the existing methodologies. To this end SFD(single flow direction method), MFD(multiple flow direction method) and IFD(Infinite flow direction method) are applied to determination of flow direction for water particles in Jeonjeokbigyo basin, and then assessed with respect to the variation of flow accumulation. As the main results the different patterns of flow accumulation are found out from each application of flow direction methods. As the flow dispersion increases on DEM contributing areas to outlet grow in sequence of SFD, IFD, MFD but contribution of individual pixels into outlet decreases. Especially MFD and IFD tend to make additional hydrologic abstraction from rainfall excess due to the flow dispersion within flow paths on DEM. Based on parameter estimation for power law distribution by maximum likelihood flow accumulation can be thought of as scale invariance factor. Combination of several flow direction methods could give rise to the more realistic water flow on DEM through separate treatment of flow direction methods for dispersion and aggregation effects of water flow within different topographies.

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Study on Behavior of Spray and Spark Channel by Air Flow Characteristics According to Operating Conditions in Gasoline Direct Injection Engine (가솔린 직분사 엔진에서 운전 조건에 따른 공기 유동 특성에 의한 분무 거동 및 점화 채널에 관한 연구)

  • Hoseung Yi;Sungwook Park
    • Journal of ILASS-Korea
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    • v.28 no.4
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    • pp.198-206
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    • 2023
  • In this study, visualization of in-cylinder spray behavior and spark channel stretching by air flow characteristics depending on engine operating conditions were investigated. For in-cylinder spray behavior, increase in engine rpm did not alter the counter-clockwise air flow direction and location of in-cylinder dominant air flow but increased average air flow velocity, which hindered spray propagation parallel to the piston surface. When injection timing was retarded, direction of in-cylinder dominant air flow was changed, and average air flow velocity was reduced resulting in an increase in spray penetration length and change in direction. For spark channel stretching, increase in air flow speed did not affect spark channel stretch direction but affected length due to increase in spark channel resistance and limitation of energy ignition coil can handle. Change in air flow direction affected spark channel stretch direction where the air flow was obstructed by ground electrode which caused spark channel direction to occur in the opposing direction of air flow. It also affected spark channel stretch length due to change in air flow speed around the spark plug electrode from the interaction between the air flow and ground electrode.

Analysis of Variation for Drainage Structure with Flow Direction Methods on the Basis of DEM (DEM을 기반으로 한 흐름방향 모의기법에 따른 배수구조의 변동성 해석)

  • Park, Hye-Sook;Kim, Joo-Cheol
    • Journal of Korean Society on Water Environment
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    • v.34 no.4
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    • pp.391-398
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    • 2018
  • The main purpose of this study is to suggest and recommend the more reliable flow direction methods within the framework of DEM and power law distribution, by investigating the existing methodologies. To this end SFD (single flow direction method), MFD (multiple flow direction method) and IFD (Infinite flow direction method) are applied to analyze the determination of a flow direction for the water particles as seen in the Jeonjeokbigyo basin, and then assessed with respect to the variation of flow accumulation in that region. As the main results revealed, the study showed the different patterns of flow accumulation are found out from each applications of flow direction methods utilized in this study. This brings us to understand that as the flow dispersion on DEM increases, in this case the contributing areas to the outlet grow in sequence of SFD, IFD, MFD, but it is noted that the contribution of individual pixels into outlet decreases at that time. In what follows, especially with the MFD and IFD, the result tends to make additional hydrologic abstraction from rainfall excess, as noted due to the flow dispersion within flow paths on DEM. Based on the parameter estimation for a power law distribution, which is frequently used for identify the aggregation structure of complex system, by maximum likelihood flow accumulation can be thought of as a scale invariance factor. In this regard, the combination of flow direction methods could give rise to the more realistic water flow on DEM, as revealed through the separate flow direction methods as utilized for dispersion and aggregation effects of water flow within the available different topographies.

Effects of flow direction on the performance of an indirect evaporative cooler (유동 방향이 간접 증발식 냉각기 성능에 미치는 영향)

  • Choo, Hyun-Seon;Lee, Kwan-Soo;Lee, Dae-Young
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.743-748
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    • 2006
  • Ren et al. analyzed the performance of the indirect evaporative cooler according to the direction of the flow considering evaporation water flow and wetness. However the effect of NTU of each channel on the performance of the indirect evaporative cooler according to the direction of the flow was not analyzed exactly. In this study the effect of the direction of the flow on the Indirect evaporative cooling performance changing NTU of each channel are investigated theoretically. The cooling process of the indirect evaporative cooler by flow direction is modeled into a set of linear differential equations and solved to obtain the exact solutions to the temperatures of the hot fluid, the moist air, and evaporation water. Based on the exact solution in the case of different NTU of each channel, we study the change of the distribution of the temperature according to each flow direction and at the same time analyze the effect of the flow direction on the cooling performance.

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Numerical analysis of plasma effect on fluid flow in a supersonic flow (플라즈마에 의한 초음속 유동 변화 해석)

  • Park, Sul-Ki;Cho, Hyung-Hee;Song, Ji-Woon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.05a
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    • pp.369-372
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    • 2009
  • A numerical analysis of the effect of plasma on flow characteristics in supersonic flow is studied. It is shown that change of direction and velocity magnitude of flow is appeared different in relative direction of plasma and fluid flow. The case of that direction of electrons, which are same with flow direction, the flow is accelerated, and the case of opposition, the flow is decelerated.

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A Study on a Direct-Type Proportional Flow Control Valve Utilizing Flowforces (유체력을 이용한 직동식 비례 유량 조절 밸브에 관한 연구)

  • 배상기;현장환;이정오
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.4
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    • pp.68-75
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    • 1998
  • A one-stage direction and flow control valve was studied theoretically and experimentally. A direction and flow control valve maintains a constant flow rate by changing the spool-orifice area under the variation of valve pressure drop, since the spool-orifice area is varied by the action of flowforces on the spool. A direction and flow control valve has the advantage of simple and low-cost structure compared to a conventional flow control valve utilizing a pressure regulating spool which regulates the pressure drop caused by flow through the metering orifice. The static and dynamic characteristics of a one-stage direction and flow control valve was analyzed. Experimental results on the flow control characteristics of the manufactured valve show satisfactory agreement with simulation results.

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Effect of Flow Direction on Two-Phase Flow Distribution of Refrigerants at a T-Junction

  • Tae Sang-Jin;Cho Keum-Nam
    • Journal of Mechanical Science and Technology
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    • v.20 no.5
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    • pp.717-727
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    • 2006
  • The present study experimentally investigated the effect of flow direction and other flow parameters on two-phase flow distribution of refrigerants at a T-junction, and also suggested a prediction model for refrigerant in a T-junction by modifying previous model for air-water flow. R-22, R-134a, and R-410A were used as test refrigerants. As geometric parameters, the direction of the inlet or branch tube and the tube diameter ratio of branch to inlet tube were chosen. The measured data were compared with the values predicted by the models developed for air-water or steam-water mixture in the literature. We propose a modified model for application to the reduced T-junction and vertical tube orientation. Among the geometric parameters, the branch tube direction showed the biggest sensitivity to the mass flow rate ratio for the gas phase, while the inlet quality showed the biggest sensitivity to the mass flow rate ratio among the inlet flow parameters.

Image Analysis for the Simultaneous Measurement of Underwater Flow Velocity and Direction (수중 유속 및 유향의 동시 측정을 위한 이미지 분석 기술에 관한 연구)

  • Dongmin Seo;Sangwoo Oh;Sung-Hoon Byun
    • Journal of Sensor Science and Technology
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    • v.32 no.5
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    • pp.307-312
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    • 2023
  • To measure the flow velocity and direction in the near field of an unmanned underwater vehicle, an optical measurement unit containing an image sensor and a phosphor-integrated pillar that mimics the neuromasts of a fish was constructed. To analyze pillar movement, which changes with fluid flow, fluorescence image analysis was conducted. To analyze the flow velocity, mean force analysis, which could determine the relationship between the light intensity of a fluorescence image and an external force, and length-force analysis, which could determine the distance between the center points of two fluorescence images, were employed. Additionally, angle analysis that can determine the angles at which pixels of a digital image change was selected to analyze the direction of fluid flow. The flow velocity analysis results showed a high correlation of 0.977 between the external force and the light intensity of the fluorescence image, and in the case of direction analysis, omnidirectional movement could be analyzed. Through this study, we confirmed the effectiveness of optical flow sensors equipped with phosphor-integrated pillars.

Interpertation of Doppler Indicies in Neurosonologic Examinations (신경초음파 검사에서 Doppler소견의 판독)

  • Kim, Jei
    • Annals of Clinical Neurophysiology
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    • v.1 no.1
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    • pp.47-54
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    • 1999
  • The Doppler in neurosonologic examination could be applied to blood flow to determine its movement, the direction of its movement, and how fast it is. Indicies of the Doppler study denoted velocity, direction, and amount of RBC in the examined vessel. Systolic. diastolic, and mean blood flow velocities represent velocity of RBCs in a sample volume. Blood flow direction to the probe means direction of RBC to the probe. Size of amplitude displays toe amount of the RBCs passing the sample volume. Spectral broadening means presence of turbelence. The RBC movements and hemodynamics at the examined vessels can be estimated by analysis of Doppler indicies The formation and meaning of each of neurosonologic Doppler study is described in the present review.

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