Flow inducer

Capillary pressure gradients and Marongoni flow induce flow in porous media comprising glass beads or sand particles [40-42], Wetting and spreading processes are an important consideration in the development of inkjet inks and paper or transparency media [43] see the article by Marmur [44] for analysis of capillary penetration in this context. 

Figure A3.14.15. The difTerential flow-induced chemical instability (DIFICI) in the BZ reaction. (Reprinted with pennission from [44], C5 The American Physical Society.)...

Bellows can vibrate, both from internal fluid flow and externally imposed mechanical vibrations. Internal flow liner sleeves prevent flow-induced resonance, which produces bellows fatigue failure in minutes at high flow velocities. Mechanically induced resonant vibration is avoided by a bellows with a natural frequency far away from the forcing frequency, if known. Multiple-ply bellows are less susceptible to vibration failure because of the damping effect of interply friction. 

Fig. 8. Transverse cross-sectional view of double-flow induced-draft cooling tower. Courtesy of The Madey Co.

Flow-induced tube vibration occurs at critical fluid velocities through tube banks, and is to be avoided because of the severe damage that can result. Methods to predict and correct vibration problems may be found in Eisinger Trans. ASME J. Pressure Vessel Tech., 102, 138-145 [May 1980]) and Chen J. Sound Vibration, 93, 439-455 [1984]). 

Fathollahi, B. and White, J. L., Polarized-light observations of flow-induced... 

Keller, A. and Kolnaar, H.W.H. (1997) Flow-induced orientation and structure formation, in Processing of Polymers, ed. Meijer, H.E.H. Materials Science and Technology, A Comprehensive Treatment, eds. Cahn, R.W., Haasen, P. and Kramer, E.J. (VCH, Weinheim) p. 189. 

Katz and Scott used equation (7) to calculate diffusivity data from measurements made on a specially arranged open tube. The equation that explicitly relates dispersion in an open tube to diffusivity (the Golay function) is only valid under condition of perfect Newtonian flow. That is, there must be no radial flow induced in the tube to enhance diffusion and, thus, the tube must be perfectly straight. This necessity, from a practical point of view, limits the length of tube that can be employed. 

Wygnanski, 1. 1964. The flow induced by two-dimensional and axisymmetric turbulent jets issuing normally from an infinite plane surface. Aeronautical Quarterly, November, pp. 373-580. 

The original design was based on a control velocity recommended by dust control design manuals. The original design of 28 m s exhaust flow induced an inward velocity of about 0.5 m s" through the enclosure entrance and trolley shots. This was not sufficient to overcome plume trajectories aimed outward, or to overcome the effect of moderate wind levels. 

We thus have a means of describing, albeit approximately, the fluid flow induced by the system in terms of the Verhoff formulae and a graphic relationship between the offset jet parameters and the equivalent wall jet parameters. We now wish to be able to calculate the movement of the contaminant in the system... 

This aspect is not included here, but is related to optical flow diagnostics. It is based again on the principle of the optical Doppler effect. Multifunctional equipment is available for noncontact measurements of flow-induced vibration on surfaces of structural elements, for acoustic measurements, and for calibration of accelerometers and vibration transducers. 

We expect more insight from simulations in the future, particularly in situations where these multicomponent systems show effects of coupling between the different degrees of freedom, surface tensions depending on temperature and concentration, hydrodynamic flow induced by concentration gradients in addition to thermal buoyancy. 

L. Biihler, S. H. Davis. Flow induced changes of the morphological stability in directional solidification localized morphologies. J Crystal Growth 756 629, 1998 Y.-J. Chen, S. H. Davis, Directional solidification of a binary alloy into a cellular convective flow (unpublished). Applied Math Technical Report No. 9708, Northwestern University, Evanston, IL 60208. 

The formation of a fibrillar structure in TLCP blends makes the mechanical properties of this kind of composites similar to those of conventional fiber reinforced thermoplastics [11,26]. However, because the molecular orientation and fibrillation of TLCPs are generally flow-induced, the formation, distribution, and alignment of these droplets and fibers are considerably more processing-dependent. We do not know ... 

Optionai flow Inducers available for minimum NPSH requirements.)... 

Figure 9-105. Cross-flow Induced draft cooling tower. Used by permission of The Marley Cooling Tower, a United Dominion Co.

The maximum unsupported tube spans in Table 10-6 do not consider potential flow-induced vibration problems. Refer to Section 6 for vibration criteria. 

Chenoweth, J. W. and J. Taborek, Flow-Induced Tube Vibration Data Banks for Shell-and-Tube Heat Exchangers, Heat Transfer Eng,Y. 2, Oct.-Dec. (1980) p. 28. 

Bends and tee-pieces in pipework often create locally turbulent flow. This enhances the corrosivity of the process liquid. These effects should be minimized by the use of flow straighteners, swept tees and gentle bends. Flow-induced corrosion downstream of control valves, orifice plates, etc. is sometimes so serious that pipework requires lining with resistant material for some twelve pipe diameters beyond the valve. 

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