• 제목/요약/키워드: PDA (Phase Doppler Anemometer)

검색결과 17건 처리시간 0.023초

간헐적인 연료분무의 유동특성에 관한 연구 (A Study on the Flow Characteristics of an Intermittent Fuel Spray)

  • 김원태;강신재
    • 대한기계학회논문집B
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    • 제21권9호
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    • pp.1198-1206
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    • 1997
  • The flow characteristics of an intermittent fuel injection into a stationary ambient air were investigated using gasoline. The measurements were made by two-channel, air cooling type Phase Doppler Anemometer(PDA) system (DANTEC, 750 MW). And a pintle type injector of MPI (Multi-point Port Injection) system was utilized as a fuel injector. The PDA receiver optic was set up in a 60.deg. C forward scatter arrangement to obtain the optimum scattering signal of fuel droplets. The data were obtained by synchronizing PDA system with the fuel injection period, and the axial and radial velocity and turbulent components of fuel droplets were mainly measured for the analysis of temporal and spatial distribution depending upon the fuel injection pressures.

공기유입을 고려한 2유체 분무의 구조에 관한 실험적 연구 (An Experimental Study on Structure of Air-assist Spray with Air Entrainment)

  • 채효철;김동일;오상헌
    • 한국분무공학회지
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    • 제6권1호
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    • pp.9-17
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    • 2001
  • The effect of air entrainment in twin-fluid spray structure is investigated experimentally by varing the amount of itemizing air. The air entrainment is expected to affect on droplet size and velocity, droplet number density, turbulent kinetic energy and vorticity. PDA(Phase Doppler Anemometer) and PIV(Particle Image Velocimetry) system are used to measure those important factors in analyzing spray structure. The results show that spray structure consists of three distinctive regions ; the atomizing region near nozzle, characterizing strong convective effect, the central core region where droplets are accelerated, and the spray sheath region where droplets are decelerated due to air entrainment. The local air entrainment rate is largest near nozzle, characterizing strong turbulent kinetic energy and vorticity but deceases along axial distance.

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Steady-Flow Characteristics and Its Influence on Spray for Direct Injection Diesel Engine

  • Jeon, Chung-hwan;Park, Seung-hwan;Chang, Young-june
    • Journal of Mechanical Science and Technology
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    • 제16권7호
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    • pp.986-998
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    • 2002
  • Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its influence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of DI (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -70° and 90°. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.

동시 시계열 계측에 의한 예혼합 분무화염 내 유적군 연소기구의 평가 (Evaluation of Combustion Mechanism of Droplet Cluster in Premixed Spray Flame by Simultaneous Time-Series Measurement)

  • 황승민
    • 대한환경공학회지
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    • 제31권6호
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    • pp.442-448
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    • 2009
  • 예혼합 분무화염의 유적군 연소 기구를 평가하기 위하여 레이저 가시화법, MICRO (multi-color integrated Cassegrain receiving optics) 및 PDA (phase Doppler anemometer) 광학계측 시스템을 이용하여 동시 시계열 계측을 실시하였다. 또한 유적군의 군연소수를 실험적으로 산출하여 이론해석에 적용하였을 경우 실제로 관찰되는 군연소 형태와 일치하는지에 대하여 검토하였다. 유적군 단면화상에 의해 확인된 모든 유적군에 대하여 실험적으로 군연소수 $G_c$를 산출한 결과 주로 내부 군연소와 외부 군연소로 분류되었으며 이론해석과 일치하였다. 또한 실제 관찰된 군연소 형태와 그 유적군의 군연소수를 이론해석에 적용한 경우에 군연소 형태가 일치하는 경우와 일치하지 않는 경우가 있었다. 일치하지 않는 원인은 군연소수를 유적의 기하학적 배치만으로 결정한 것이나 현상의 3차원성이 측정 결과에 영향을 미친 것이라고 생각되어진다.

유체의 물성치 변화가 압력스월노즐 분무의 속도와 입경에 미치는 영향 (Effects of Different Fluid Properties on Velocity and Size of Droplets from Pressure-Swirl Nozzles)

  • 최윤철;손종원;차건종;김덕줄
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집D
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    • pp.909-914
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    • 2001
  • Fluid properties which are most commonly used to evaluate spray atomization characteristics, are important because they affect velocity and size distribution of droplets. The purpose of this study was to incorporate the significant characteristics in atomization process of industrial etching spray and how each of them affects the design of precise pressure-swirl nozzles. The experiment was carried out with different viscosity and density of fluid. The macro characteristics of liquid spray, such as the spray angle and shape were captured by PMAS and the micro characteristics of liquid spray, such as droplet size and velocity were obtained by PDA. The mean velocity and SMD of droplets were measured along axial and radial direction. It was found that the higher viscosity and density resulted in the larger SMD and the lower mean velocity of droplets.

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에칭시스템에서 요동각 변화에 따른 에칭특성 시뮬레이션 (Simulation of Etching Characteristics with Oscillation Angle in Etching System)

  • 정흥철;김영진;정지원;김덕줄
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 춘계학술대회
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    • pp.1534-1539
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    • 2004
  • The objective of this study is to simulate the etching characteristics with oscillation angle for the optimization of etching system. The etching characteristics were analyzed under different etching conditions. The spray characteristics were measured by Phase Doppler Anemometer (PDA). The correlation between the spray characteristics and the etching characteristics was investigated and used for fundamental data to simulate the etching characteristics with oscillation angle. The smaller coefficient of variation, the more uniform etching characteristic distribution became. It was found that numerical predictions of etching factor generally agreed well with the measured results with distance from nozzle tip. Oscillation leads to decrease of etching factor and increase of uniformity.

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The Precision of Lead Frame Etching Characteristics Using Monte-Carlo Simulations

  • Jeong, Heung-Cheol;Choi, Gyung-Min;Kim, Duck-Jool
    • International Journal of Precision Engineering and Manufacturing
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    • 제8권1호
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    • pp.73-78
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    • 2007
  • The objective of this work was to simulate lead frame etching characteristics to optimize the etching process, Characteristics such as the etching factor and uniformity were investigated for different actual operating conditions, including pressure, distance from the nozzle tip, pipe pitch, and feed speed. The correlation between the etching and spray characteristics was analyzed to develop the etching model. Spray characteristics obtained from an experiment using a phase Doppler anemometer system were then simulated using a Monte-Carlo technique, The etching process model was coded in the Java language, The spray and etching characteristics were correlated with each other and simulated results agreed well with the measured data for a lead frame etching process, The optimal operating parameters under various conditions were successfully determined.

Application of Light Collecting Probe with High Spatial Resolution to Spark-Ignited Spherical Spray Flames

  • Yang, Young-Joon;Akamatsu, Fumiteru;Katsuki, Masashi
    • Journal of Mechanical Science and Technology
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    • 제18권11호
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    • pp.2058-2065
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    • 2004
  • A light collecting probe named Multi-color Integrated Cassegrain Receiving Optics (MICRO) is applied to spark-ignited spherical spray flames to obtain the flame propagation speed in freely falling droplet suspension produced by an ultrasonic atomizer. Two MICRO probes are used to monitor time-series signals of OH chemiluminescence from two different locations in the flame. By detecting the arrival time difference of the propagating flame front, the flame propagation speed is calculated with a two-point delay-time method. In addition, time-series images of OH chemiluminescence are simultaneously obtained by a high-speed digital CCD camera to ensure the validity of the two-point delay-time method by the MICRO system. Furthermore, the relationship between the spray properties measured by phase Doppler anemometer (PDA) and the flame propagation speed are discussed with three different experimental conditions by changing the fuel injection rate. It was confirmed that the two-point delay-time method with two MICRO probes is useful and convenient to obtain the flame propagation speed and that the flame propagation speed depends on the spray properties.

저압 분사시 캐비테이션에 의한 단공 노즐의 미립화 향상 (The Enhacned Atomization of Single Hole Nozzle by Cavitation at The Low Pressure Injection)

  • 손종원;차건종;김덕줄
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집B
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    • pp.952-957
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    • 2001
  • The objectives of this investigation were to obtain an excellent spray by cavitation under the low injection pressure. When cavitation occurs in the nozzle hole, the atomization of the liquid jet enhanced considerably. In this experiments, a acrylic nozzle made the gap and installed the bypass in the nozzle hole was used to enhance the atomization of the liquid jet at the low injection pressure. The liquid flow in the nozzle hole was photographed by a transmitted light using a micro flash. The spray angle was measured macroscope images of PMAS and the Sauter mean diameter was measured PDA system. To measure the pressure of the nozzle hole, pressure transducer was used. The results of this study indicated that enhanced atomization of the liquid jet at the low injection pressure was obtained by making the gap and installing the bypass at the single hole nozzle.

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Experimental Study on Spray Etching Process In Micro Fabrication of Lead Frame

  • Jung, Ji-Won;Choi, Gyung-Min;Kim, Duck-Jool
    • Journal of Mechanical Science and Technology
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    • 제18권12호
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    • pp.2294-2302
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    • 2004
  • The objective of this study is to obtain detailed information for the micro fabrication of lead frames by applying spray technology to wet etching process. Wet etching experiments were performed with different etching parameters such as injection pressure, distance from nozzle tip to etched substrate, nozzle pitch and etchant temperature. The characteristics of single and twin spray were measured to investigate the correlation between the spray characteristics and the etching characteristics. Drop size and velocity were measured by Phase-Doppler Anemometer (PDA). Four liquids of different viscosity were used to reveal the effects of viscosity on the spray characteristics. The results indicated that the shorter the distance from nozzle tip and the nozzle pitch, the larger etching factor became. The average etching factor had good positive correlation with average axial velocity and impact force. It was found that the etching characteristics depended strongly on the spray characteristics.