Flow structure, droplet formation and dispersion when an interface separating immiscible fluids is impinged with a vertical negatively buoyant jet
- 出版日期：2002.
- 页数：213 p. :
- 第一责任说明：Peter Daniel Friedman.
- 分类号：a141.4
- ISBN：0493606440(ebk.) :
MARC全文
02h0026013 20111122105030.0 cr un||||||||| 111122s2002 xx ||||f|||d||||||||eng | AAI3046454 0493606440(ebk.) : CNY371.35 NGL NGL NGL a141.4 Friedman, Peter Daniel. Flow structure, droplet formation and dispersion when an interface separating immiscible fluids is impinged with a vertical negatively buoyant jet [electronic resource] / Peter Daniel Friedman. 2002. 213 p. : digital, PDF file. Source: Dissertation Abstracts International, Volume: 63-03, Section: B, page: 1527. ; Adviser: Joseph Katz. Thesis (Ph.D.)--The Johns Hopkins University, 2002. Includes bibliographical references. This dissertation summarizes a series of experiments to determine the effects of impinging a water and diesel fuel interface with a negatively buoyant water jet. The maximum depth that the jet penetrates is only a function of a pipe exit Richardson number divided by a jet spreading factor, which is only a function of distance between the jet exit and the interface. As long as the jet is turbulent, the penetration depth is independent of Reynolds and Weber numbers. A universal correlation developed in this study relates the penetration depth of jets in any fluid systems.;The macroscopic flow structure is categorized into distinct flow regimes that are dependent on an interface Richardson number, Rii. At high Rii the jet forms a smooth and stable deformation in the interface with no flow separation and no droplet formation. At moderate Rii the deformation becomes taller and steeper and a flow separation develops at its edge. An oil lip created at the flow separation sometimes detaches to form oil droplets in the water below. At lower Rii the deformation becomes unstable and alternately collapses and reforms. Droplets result when the collapsing deformation impacts the interface and drags down fingers of oil. Droplet size distributions are lognormal and depend on Rii, Re , viscosity ratio and Morton number. Mode diameters range from 0.6mm to 1.5mm.;Experiments demonstrate that the mean droplet rise-rate, Ū , varies between 0.2 to five times the rise-rate in quiescent fluid, Uq, increasing with decreasing diameter. At high turbulence intensity, u′, Ū asymptotically approaches 0.25u′, while at low u′, Ū asymptotically approaches Uq. At intermediate u′, Ū is a strong function of Stokes number, St. In this case, at low St, Ū = Uq, while at high St, Ū << Uq. Data from this study is the first to show an enhancement of rise-rate of droplets that are less dense than the continuous phase. Trends are explained in terms of trajectory biasing and non-linear drag effects. Fluid dynamics. Electronic books. aeBook. aCN bNGL http://proquest.calis.edu.cn/umi/detail_usmark.jsp?searchword=pub_number%3DAAI3046454&singlesearch=no&channelid=%CF%B8%C0%C0&record=1 NGL Bs1056 rCNY371.35 ; h1 bs1108