• 제목/요약/키워드: Spray time

검색결과 828건 처리시간 0.028초

와류형 고압 분무의 속도 및 입경분포에 관한 연구 (A Study on the Distribution of Droplet Velocity and Diameter in a High-Pressure Swirl Spray)

  • 최동석;류경훈;차건종;김덕줄
    • 대한기계학회논문집B
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    • 제23권10호
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    • pp.1310-1319
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    • 1999
  • High-pressure swirl injectors have usually been employed in Gasoline direct injection engines due to their spray characteristics and the feasibility of their control. Thus the microscopic characteristics of high-pressure swirl spray were investigated by PDA. The correlation between axial and radial velocities and the correlation between droplet size and axial velocity were examined with different axial and radial positions. Two dimensional droplet velocity and its number distribution with size-classified droplets were illustrated. The mean droplet velocity and its SMD were also analyzed at the center of spray, the position having maximum mean axial velocity, and the spray periphery using time dividing method. Finally, the structure of high-pressure swirl spray was presented with the size distribution and velocity profile of droplets.

커먼레일을 이용한 디젤과 BD20 연료가 인젝터에 미치는 영향에 관한 연구 (A Study on Injector Durability Test with Diesel and BD20 Using Common Rail)

  • 정연호;임옥택
    • 한국수소및신에너지학회논문집
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    • 제26권5호
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    • pp.393-401
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    • 2015
  • The characteristics of diesel and biodiesel are similar like as cetane number and auto-ignition temperature. High cetane number of diesel and BD could make possible to compression ignition. but BD showed different atomization from diesel due to component like density, viscosity and iodine value etc. Because of this, the biodiesel requires validation. This study using diesel and BD20 investigated effect to durability injector. Durability test were used common rail and bosch solenoid type 5-hole injector. Total test was 672hr but actual running time was 200hr. Spray experiments for spray characteristics were carried out using constant volume combustion chamber. Spray characteristics of diesel and BD showed different result up to durability test time. After 100hr, diesel showed spray shapes were stable but BD was not. After 200hr, difference of diesel and BD spray shapes were grow serious.

광폭면 분무를 위한 2유체 노즐의 분무 특성에 관한 연구 (An Experimental Study on the Spray Characteristics by Twin-Fluid Atomizer for Wide Band Spray)

  • 이중순
    • 한국분무공학회지
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    • 제13권4호
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    • pp.212-219
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    • 2008
  • To develop the twin-fluid atomizer having the excellent performance of painting, the spray characteristics of how a wide area can be painted efficiently by one time spraying were studied in this paper. Spray phenomena are affected by the many factors determining the spray field such as the spraying pressure of gas, the spraying pressure and viscosity of liquid paints, the opening duration of needle valve, the design dimension of nozzle, and so on. As the results of experiments, these factors affecting on spray characteristics were suggested as followings; 1) The optimum spraying pressure of gas was $0.015{\sim}0.02\;kPa$, and the appropriate spraying pressure of liquid paint was 0.01kPa, In these situations, the setting up pressures must be compensated as much as the losing amount of pressure because a decompression occurred when operating valves. 2) The duration of opening the needle valve must be sustained for $1{\sim}2$ seconds to inject gas after spraying the liquid paint. This operating of the needle valve was necessary to avoid the affect on the changing of liquid column length, and to prevent the droplet deposit at the initial time of spraying. 3) The spray tip penetration was gained form the experimental equation, and the effective spraying angle was $85^{\circ}{\pm}5^{\circ}$ just at he appropriate spraying pressure of gas. The distribution of the area sprayed had the variation in $350{\pm}50\;mm$ because of the spraying pressure of gas, the its distance from the spray tip, and the lift of the needle valve.

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에폭시 프라이머 도료의 에어리스 스프레이 분사 시간에 따른 팁 노즐 침식마모경향과 분사특성 연구 (A study on the erosive wear of spray tip nozzle by epoxy primer paint impingement and the spraying characteristics)

  • 김진억;조연호;천제일;한명수
    • Corrosion Science and Technology
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    • 제14권2호
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    • pp.59-63
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    • 2015
  • Airless spray which is widely used for painting to ship blocks and hull sides is the coating method for attaching atomized paint material to the substrate using spray tip nozzle with compressed air. When the paint material which has high solid contents such as epoxy primer paint is atomized by passing through spray tip nozzle with high pressure, the nozzle composed of tungsten carbide(WC) undergoes the erosive wear, leading to widening of nozzle hole. The deformation of nozzle hole induces improper spray pattern and coating failures such as finger pattern and sagging because the conditions of spray pump pressure and paint flow rate for developing full spray pattern are changed. In this study, an appropriate replacement cycle of spray tip was predicted by measuring the erosive wear tendency as increasing the spraying time of epoxy primer paint.

비정상 충돌 분류의 Cavity형상에 따른 공간 농도 분포 및 거동해석 (The Spray Behavior Analysis and Space Distribution of Mixture in Transient Jet Impinging on Piston Cavity)

  • 이상석;김근민;김봉곤;정성식;하종률
    • 한국분무공학회지
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    • 제1권2호
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    • pp.16-23
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    • 1996
  • In case of a high-speed D.I. diesel engine. the injected fuel spray is unavoidable that the impinging on the wall of piston cavity and in this case the geometry of piston cavity has a great influence on the atomization structure and air flow fields. In the field of combustion and in many other spray applications, there are clear evidence of correlation between spray structure and emission of pollutants. Ordinary, the combustion chamber of driving engine have unsteady turbulent flow be attendant on such as the change of temperature, velocity and pressure. So the analysis of spray behavior is difficult. In this study, a single spray was impinged on each cavity wall at indicated angle in a quiescent atmosphere at room temperature and pressure, as being the simplest case, and 3 types of piston cavity such as Dish, Toroidal and Re-entrant type was tested for analyzing the influence of cavity geometry. And hot wire probe was used for analyze non-steady flow characteristics of impinging spray, and to investigate the behavior of spray, the aspects of concentration c(t), standard deviation $\sigma(t)$ and variation factor (v.f.) was measured with the lapse of time.

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Correlations for Prediction of Non-evaporating Diesel Spray Penetration

  • No, Soo-Young
    • 한국분무공학회지
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    • 제12권3호
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    • pp.146-153
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    • 2007
  • The prediction of diesel spray penetration has been the subject of several works and intensive investigations are still underway by many researchers. It is required to summarize the correlations developed before 1990 days and to introduce the correlations reported recently in the literature. The existing zero-dimensional models for the prediction of diesel fuel spray penetration can be classified as theoretical and empirical correlations. Of various correlations, the models considered in this paper were selected as based on the evaluation results of previous reviews and the recently published works in the literature. The existing theoretical correlations can be classified into seven categories and the existing empirical ones as two categories in this review. According to the review of existing models, the dominating factors for the prediction of spray tip penetration are the spray angle, discharge coefficient, pressure drop across nozzle, ambient density and orifice diameter and time after the start of injection. Especially, the definition for the measurement of spray angle is different with researchers. It is required to evaluate the existing spray tip penetration models for the very high injection pressure and other fuel sprays such as DME. It is also required to evaluate the correlations for the prediction of diesel spray penetration with the connection of liquid-phase penetration.

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디젤분무에 대한 액체미립화모델들의 영향 (The Influence of Liquid Atomization Models on Diesel Sprays)

  • 이성혁;유홍선;홍기배
    • 한국자동차공학회논문집
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    • 제8권6호
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    • pp.22-30
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    • 2000
  • The present article deals with comparisons of published liquid breakup models for diesel sprays to analyze the influence of breakup models on various spray parameters. The three different models tested in this study are the surface wave instability (Wave) model, the Taylor analogy breakup (TAB) model, and the drop drag model(DDM). The numerical results using these models are compared with several experimental data to assess the prediction capabilities of breakup models. Additional task in this study is to investigate effects of the breakup time constant in the Wave model on the spray parameters because the spray behavior is sensitive to the breakup time constant. It is seen that there is uncertainly about the breakup time constant indicating that the suitable acceptance of the constant is important, and the TAB model generally shows significant under-prediction of Sauter Mean Diameter(SMD). In addition, it may be indicated that differences between the DDM and Wave model are not significant, showing that the DDM may be suitable for air-assisted atomization rather than pressure atomization.

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3D 스캔 시 품질향상을 위한 스프레이 도포 자동화 장비 개발 (Development of Auto-spray system to improve the quality of 3D Scanning Quality)

  • 김원섭;조재흥;김동수;김동규;홍석무
    • 한국산학기술학회논문지
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    • 제17권4호
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    • pp.100-105
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    • 2016
  • 3D 프린터의 증가에 따라 대량 생산이 아닌 소량 제품의 빠른 개발 시간을 고려하여 3D 스캐너의 활용도 점차 증가하고 있다. 소량 생산 개발 트렌드뿐만 아니라 최근 자동차 및 전자부품의 제조업에 있어서도 정밀 부품의 개발 및 검사, 측정 등의 품질 문제가 중요한 이슈로 떠오르고 있다. 최근 3D 스캐너 장비 효율성 및 인식기술은 지속적으로 향상되었지만, 이에 반해, 이를 준비하는 스프레이 작업은 시간이 많이 걸리고 환경문제가 유발되기 때문에 제조업 제품 개발자들은 자동스프레이 도포 시스템 개발에 대해 지속적으로 요구해 왔다. 본 연구를 통해서 3D 스캔 준비 작업으로 필요한 스프레이 자동 도포 장비를 개발하였으며, 스프레이 도포 시 균일하게 미세 분말이 도포 될 수 있도록 파라미터 세팅에 대해 실험적으로 연구하였다. 결과적으로 빠르고 쉬운 자동 스프레이 도포 장비가 개발 되었고, 이를 활용해서 3D 측정을 위한 준비 시간이 기존 대비 1/10수준으로 단축되었다. 또한 다양한 조건에 대한 비교를 통해 최적의 도포 조건을 실험적으로 제시하였다.

고압에서의 분무의 증발 및 연소 현상에 관한 연구 (Study on Vaporization and Combustion of Spray in High Pressure Environment)

  • 왕태중;백승욱
    • 대한기계학회논문집B
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    • 제27권9호
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    • pp.1273-1281
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    • 2003
  • The present study is mainly motivated to investigate the vaporization, auto-ignition, and combustion of liquid fuel spray injected into high pressure environment. The unsteady, multi-dimensional models were used for realistic simulation of spray as well as prediction of accurate ignition delay time. The Separated Flow (SF) model which considers the finite rate of transport between liquid and gas phases was employed to represent the interactions between spray and gas field. Among the SF models, the Discrete Droplet Model (DDM) which simulates the spray using finite number of representative samples of discrete droplets was adopted. The Eulerian-Lagrangian formulation was used to analyze the two-phase interactions. In order to predict an evaporation rate of droplet in high pressure environment, the high pressure vaporization model was applied using thermodynamic equilibrium and phase equilibrium at droplet surface. The high pressure effect as well as high temperature effect was considered in the calculation of liquid and gas properties. In case of vaporization, an interaction between droplets was studied through the simulation of spray. The interaction is shown up differently whether the ambient gas field is at normal pressure or high pressure. Also, the characteristics of spray behavior in high pressure environment were investigated through the comparison with normal ambient pressure case. In both cases, the spray behaviors are simulated through the distributions of temperature and reaction rate in gas field.

PistonCavity 형상에 따른 충돌분류의 분무거동 (The Behavior of Impinging Spray by Piston Cavity Geometry)

  • 이상석;김근민;김봉곤;정성식;하종률
    • 한국자동차공학회논문집
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    • 제4권3호
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    • pp.211-219
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    • 1996
  • In a small high-speed D. I. diesel engine, the injected fuel spray into the atmosphere of the high temperature is burnt by go through the process of break up, atomization, evaporation and process of ignition. These process are important to decide the emission control and the rate of fuel consumption and out put of power. Especially, in the case of injected fuel spray impinging on the wall of piston cavity, the geometry of piston cavity gives great influence the ignitability of injected fuel and the flame structure. Ordinary, the combustion chamber of driving engine have unsteady turbulent flow be attendant on such as the change of temperature, velocity and pressure. So the analysis of spray behavior is difficult. In this study, the spray was impinged on the wall of 3 types of piston cavity such as Dish, Toroidal, Re-entrant type, in order to analyze the combustion process of impinging spray precisely and systematically. And hot wire probe was used for analyze non-steady flow characteristics of impinging spray, and to investigate the behavior of spray, the aspects of concentration c(t), standard deviation σ(t) and variation factor(vf) was measured with the lapse of time.

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