• Title/Summary/Keyword: Particle dispersion

Search Result 658, Processing Time 0.031 seconds

Effect of oil particle size on dispersion stability in oil in water emulsion (Oil in Water 에멀전에서 오일 입자 크기가 분산 안정성에 미치는 영향)

  • Hwangbo, Sunae;Chu, Minchul;Moon, Changkwan
    • Particle and aerosol research
    • /
    • v.13 no.3
    • /
    • pp.133-139
    • /
    • 2017
  • In this paper, we proposed an emulsification method without using an emulsifier and investigated the effects of particle size distribution in fluids on dispersion stability. Surfactant-free oil in water emulsion was prepared with 1 % (w/w) of olive oil by using high speed agitation, high pressure and ultrasonic dispersion methods. The particle size, microscopic observation, and dispersion stability of each sample were evaluated and dispersion stability according to various dispersion methods was compared. As a result, the emulsion dispersed by the ultrasonic dispersion method showed the smallest particle size and uniform distribution of $0.07{\sim} 0.3{\mu}m$ and was the most stable in a 7 days stability evaluation. In the above experiment, four olive oil emulsions having different particle sizes were prepared using ultrasonic dispersion technology that was capable of producing stable emulsions. The dispersion stability of each samples with oil droplet sizes of (A) 0.1 to $0.5{\mu}m$, (B) 0.3 to $4{\mu}m$, (C) 1 to $10.5{\mu}m$ and (D) 2 to $120{\mu}m$, was observed for 7 days, and the relationship between the stability and performance was studied. Emulsion (A) with particle size less than $0.5{\mu}m$ displayed the dispersion stability showing below 5 % change in a 7 days stability evaluation. In the case of (B), (C), and (D) that had larger particle than $0.5{\mu}m$, the changes of dispersion stability were 10 %, 13 % and 35 % respectively. From these results, it was proved that dispersion stability of emulsion with uniform particle size of $0.5{\mu}m$ or less was confirmed to be very stable.

Dispersion Characteristics of Nonspherical Fume Micro-Particles in Laser Line Machining in Terms of Particle Sphericity (입자 구형도에 따른 레이저 선가공의 비구형 흄 마이크로 입자 산포 특성 연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Semiconductor & Display Technology
    • /
    • v.21 no.2
    • /
    • pp.1-6
    • /
    • 2022
  • This computational investigation of micro-sized particle dispersion concerns the fume particle contamination over target surface in high-precision laser line machining process of semiconductor and display device materials. Employing the random sampling based on probabilistic fume particle generation distributions, the effects of sphericity for nonspherical fume particles are analyzed for the fume particle dispersion and contamination near the laser machining line. The drag coefficient correlation for nonspherical particles in a low Reynolds number regime is selected and utilized for particle trajectory simulations after drag model validation. When compared to the corresponding results by the assumption of spherical fume particles, the sphericity of nonspherical fume particles show much less dispersion and contamination characteristics and it also significantly affects the particle removal rate in a suction air flow patterns.

Numerical Evaluation of charged Liquid Particle′s Behavior in Fluid Flow and Electric Field and The Electric Effect on the Particle Dispersion (유동과 전기장 내에서의 액체입자의 거동과 전기장이 입자의 산란에 미치는 영향에 관한 수치적 연구)

  • Kim, Hyeong-Min
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.26 no.4
    • /
    • pp.570-577
    • /
    • 2002
  • Charged liquid particle's behavior in electric and flow field was simulated to define the effect of electric field on the contact area and its dispersion. For the simulation of flow and electric field finite volume method was applied. To find out the particle's moving path in that field lagrangian equation of motion was solved by Runge-Kutta methods. We assumed that the particle was charged 10% of Rayleigh limit while the particle passing through the electrode and the particle does not have an effect on the electric field. In case of 30[Kv] of voltage charging the particles injected from the central 60% of the nozzle injection area adhere to the grounded moving plate and no dispersion occurred. Increasing the charged voltage to 40[Kv], it brought about the same phenomena as that of 30[Kv] charging except the dispersion. Voltage increasing from 30[Kv] to 40 [Kv] caused higher Coulomb force acts on the particle and it made the particle dispersion.

Fume Particle Dispersion in Laser Micro-Hole Machining with Oblique Stagnation Flow Conditions (경사 정체점 유동이 적용된 미세 홀 레이저 가공 공정의 흄 오염입자 산포특성 연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Semiconductor & Display Technology
    • /
    • v.20 no.3
    • /
    • pp.77-82
    • /
    • 2021
  • This numerical study focuses on the analysis of fume particle dispersion characteristics over the surface of target workpiece in laser micro-hole machining process. The effects of oblique stagnation flow over fume generating machining point are examined by carrying out a series of three-dimensional random particle simulations along with probabilistic particle generation model and particle drag correlation of low Reynolds number. Present computational model of fume particle dispersion is found to be capable of assessing and quantifying the fume particle contamination in precision hole machining which may influenced by different types of air flow patterns and their flow intensity. The particle size dependence on dispersion distance of fume particles from laser machining point is significant and the effects of increasing flow oblique angle are shown quite differently when slot blowing or slot suction flows are applied in micro-hole machining.

Numerical study of Particle Motion in a Developing Mixing Layer using Large-eddy Simulation (LES를 이용한 발전하는 혼합층에서의 입자 운동에 관한 수치 해석 연구)

  • Kim, Tae-Jin;Seo, Tae-Won
    • Proceedings of the KSME Conference
    • /
    • 2001.06e
    • /
    • pp.94-99
    • /
    • 2001
  • The numerical simulation of the particle dispersion in the vortical flows provides insight into the mechanism of particle-fluid interaction. The simulation results show that the mixing layers are characterized by the large-scale vortical structures undergoing pairing process. The particle dispersion is strongly influenced by the large-scale structures and the particle sizes. The analysis shows that the mixing layers grows like a step-function.

  • PDF

A Study on the Dispersion of Fuel Particles in the Homogeneous Turbulent Flow Field (균일 난류 유동장내에서 연료입자의 퍼짐에 관한 연구)

  • 김덕줄;최연우
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.18 no.5
    • /
    • pp.1330-1337
    • /
    • 1994
  • This study is to predict the lateral dispersion of the particles with time in a vertical pipe. Particle is released downward and located in the center of a pipe through which stationary, homogeneous turbulent air is flowing. We assume that gas turbulence velocities have a Gaussian probability density distribution and the presence of particle is not to alter turbulent structures. Particle trajectory is computed by numerically integrating the particle Lagrangian equation of motion, with a random sampling to determine the fluctuating air velocity experienced by each particle, which considered inertia effect and crossing-trajectories effect. The result shows characterestics of particle dispersion according to flow field condition and droplet size by using the parameters and scales, which expressed characterestics of flow field and particle. Predictions agree reasonably with experimental data.

Effect of Dispersion Stability of Particles on Detergency of Particulate Soil(Part 1) - The Dispersion Stability of α-Fe2O3 Particles in the Nonyl Phenol Polyoxyethylene Ether Solution - (입자의 분산안정성이 고형오구의 세척성에 미치는 영향(제1보) - Nonyl Phenol Polyoxyethylene Ether 용액 내에서 α-Fe2O3 입자의 분산안정성 -)

  • Kang, In-Sook
    • Fashion & Textile Research Journal
    • /
    • v.4 no.1
    • /
    • pp.86-91
    • /
    • 2002
  • To estimate dispersion stability of particles, suspending power and particle size were examined as functions of pHs, surfactants, electrolytes and ionic strengths using ${\alpha}-Fe_2O_3$ particle as the model of particulate soil. Suspending power and particle size were determined by UV-Vis spectrumeter and by light scattering using the polarization ratio method, respectively. The suspending power was relatively high with polyanion electrolytes and was low with neutral salts. The suspending power was biphasis, minimum pH 6~7, and the effect of surfactant on the suspending power was insignificant. Generally suspending power increased with decreasing the particle size governed aggregation of dispersed particles regardless of solution conditions. Hence the suspending power was inversely related to the particle size.

Downward and Upward Air Flow Effects on Fume Particle Dispersion in Laser Line Cutting of Optical Plastic Films

  • Kim, Kyoungjin
    • Journal of the Semiconductor & Display Technology
    • /
    • v.19 no.2
    • /
    • pp.37-44
    • /
    • 2020
  • In improving laser cutting of optical plastic films for mass production of optoelectronics display units, it is important to understand particle contamination over optical film surface due to fume particle generation and dispersion. This numerical study investigates the effects of downward and upward air flow motions on fume particle dispersion around laser cut line. The simulations employ random particle sampling of up to one million fume particles by probabilistic distributions of particle size, ejection velocity and angle, and fume particle dispersion and surface landing are predicted using Basset-Boussinesq-Oseen model of low Reynolds number flows. The numerical results show that downward air flow scatters fume particles of a certain size range farther away from laser cut line and aggravate surface contamination. However, upward air flow pushes fume particles of this size range back toward laser cut line or sucks them up with rising air motion, thus significantly alleviating surface contamination.

Particle Dispersion and Effect of Spin in the Turbulent Boundary Layer Flow (난류 경계층 유동에서 입자의 확산과 스핀의 영향)

  • Kim, Byung-Gu;Lee, Chang-Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.28 no.1
    • /
    • pp.89-98
    • /
    • 2004
  • In this paper, we develope a dispersion model based on the Generalized Langevin Model. Thomson's well-mixed condition is the well known criterion to determine particle dispersion. But, it has 'non-uniqueness problem'. To resolve this, we adopt a turbulent model which is a new approach in this field of study. Our model was greatly simplified under the self-similarity condition, leaving model only two model constants $C_{0}$ and ${\gamma}$$_{5}$ that control the dispersion and spin which measures rotational property of the Lagrangian particle trajectory. We investigated the sign of spin as well as magnitude by using the Direct Numerical Simulation. Model calculations were performed on the neutrally stable boundary layer flow. We found that spin has weak effect on the particle dispersion but it shows the significant effect on the horizontal flux compared to the zero-spin model.

A Development of Lagrangian Particle Dispersion Model (Focusing on Calculation Methods of the Concentration Profile) (라그란지안 입자확산모델개발(농도 계산방법의 검토))

  • 구윤서
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.15 no.6
    • /
    • pp.757-765
    • /
    • 1999
  • Lagrangian particle dispersion model(LPDM) is an effective tool to calculate the dispersion from a point source since it dose not induce numerical diffusion errors in solving the pollutant dispersion equation. Fictitious particles are released to the atmosphere from the emission source and they are then transported by the mean velocity and diffused by the turbulent eddy motion in the LPDM. The concentration distribution from the dispersed particles in the calculation domain are finally estimated by applying a particle count method or a Gaussian kernel method. The two methods for calculating concentration profiles were compared each other and tested against the analytic solution and the tracer experiment to find the strength and weakness of each method and to choose computationally time saving method for the LPDM. The calculated concentrations from the particle count method was heavily dependent on the number of the particles released at the emission source. It requires lots fo particle emission to reach the converged concentration field. And resulting concentrations were also dependent on the size of numerical grid. The concentration field by the Gaussian kernel method, however, converged with a low particle emission rate at the source and was in good agreement with the analytic solution and the tracer experiment. The results showed that Gaussian kernel method was more effective method to calculate the concentrations in the LPDM.

  • PDF