Analysis of Aerosol Particle Transport, Deposition, Removal and Resuspension in Turbulent Flows PDF Download

Author: Haifeng Zhang
Publisher:
ISBN:
Category : Particles (Nuclear physics)
Languages : en
Pages : 412

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Further progress in achieving the objectives of the project was made in the period of October 1 to December 31, 1996. In particular, the sublayer model for evaluating the particle deposition in turbulent flows was extended to include the effect of particle rebound. A new more advance flow model for the near wall vortices is also used in these analysis. The computational model for simulating particle transport in turbulent flows was used to analyze the dispersion and deposition of particles in a recirculating flow region. The predictions of the particle resuspension model is compared with the experimental data. It is shown that when the effects of the near wall flow structure, as we as the surface roughness are included the model agrees with the available experimental data. Considerable progress was also made in the direct numerical simulation of particle removal process in turbulent gas flows. Experimental data for transport and deposition of glass fiber in the aerosol wind tunnel was also obtained.

Author: Yingjie Tang
Publisher:
ISBN:
Category :
Languages : en
Pages :

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In this work, various aerosol particle transport and deposition mechanisms were studied through the computational fluid dynamics (CFD) modeling, including inertial impaction, gravitational effect, lift force, interception, and turbophoresis, within different practical applications including aerosol sampling inlet, filtration system and turbulent pipe flows. The objective of the research is to obtain a better understanding of the mechanisms that affect aerosol particle transport and deposition, and to determine the feasibility and accuracy of using commercial CFD tools in predicting performance of aerosol sampling devices. Flow field simulation was carried out first, and then followed by Lagrangian particle tracking to obtain the aerosol transport and deposition information. The CFD-based results were validated with experimental data and empirical correlations. In the simulation of the aerosol inlet, CFD-based penetration was in excellent agreement with experimental results, and the most significant regional particle deposition occurred due to inertial separation. At higher free wind speeds gravity had less effect on particle deposition. An empirical equation for efficiency prediction was developed considering inertial and gravitational effects, which will be useful for directing design of similar aerosol inlets. In the simulation of aerosol deposition on a screen, a "virtual surface" approach, which eliminates the need for the often-ambiguous user defined functions, was developed to account for particle deposition due to interception. The CFD-based results had a good agreement compared with experimental results, and also with published empirical correlations for interception. In the simulation of turbulent deposition in pipe flows, the relation between particle deposition velocity and wall-normal turbulent velocity fluctuation was quantitative determined for the first time, which could be used to quantify turbulent deposition, without having to carry out Lagrangian particle tracking. It suggested that the Reynolds stress model and large eddy simulation would lead to the most accurate simulated aerosol deposition velocity. The prerequisites were that the wall-adjacent y+ value was sufficiently low, and that sufficient number of prism layers was applied in the near-wall region. The "velocity fluctuation convergence" would be useful criterion for judging the adequacy of a CFD simulation for turbulent deposition.

Author: Chaosheng Liu
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 110

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Author: Jim Chuin Yin
Publisher:
ISBN:
Category :
Languages : en
Pages : 248

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Author: K. L. Mittal
Publisher: John Wiley & Sons
ISBN: 1118831543
Category : Technology & Engineering
Languages : en
Pages : 482

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The book provides a comprehensive and easily accessible reference source covering all important aspects of particle adhesion and removal. The core objective is to cover both fundamental and applied aspects of particle adhesion and removal with emphasis on recent developments. Among the topics to be covered include: 1. Fundamentals of surface forces in particle adhesion and removal. 2. Mechanisms of particle adhesion and removal. 3. Experimental methods (e.g. AFM, SFA,SFM,IFM, etc.) to understand particle-particle and particle-substrate interactions. 4. Mechanics of adhesion of micro- and nanoscale particles. 5. Various factors affecting particle adhesion to a variety of substrates. 6. Surface modification techniques to modulate particle adhesion. 7. Various cleaning methods (both wet & dry) for particle removal. 8. Relevance of particle adhesion in a host of technologies ranging from simple to ultra-sophisticated.

Author: William Dwight Gerstler
Publisher:
ISBN:
Category :
Languages : en
Pages : 690

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Author: W. E. Ranz
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 194

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The impactions of small particles on cylindrical and spherical collectors was analyzed in terms of the forces which affect the motion of a particle and cause it to move from an aerosol stream onto a collecting surface. Dimensionless parameters which characterize the various mechanisms of collection are defined for inertial separation, interception, electrical attraction, and random molecular motion. Significant values of the parameters were determined. The various theories of impaction of aerosol particles on simple collectors were investigated and extended to a comprehensive statement of the general problem of impaction efficiencies. Practical applications to dust and smoke removal systems are indicated.

Author: Chunyu Jin
Publisher:
ISBN:
Category :
Languages : en
Pages : 244

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Author: James A. Gieseke
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 44

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