Vortex generator characteristics

Friction loss from sodden expansion of cross section. If the cross section of the conduit is suddenly enlarged, the fluid stream separates from the wall and issues as a jet into the enlarged section. The jet then expands to fill the entire cross section of the larger conduit. The space between the expanding jet and the conduit wall is filled with fluid in vortex motion characteristic of boundary-layer separation, and considerable friction is generated within this space. This effect is shown in Fig. 5.13. 

Combined vortex generator (Figurel5.3) (Kutateladse, 1976 Mamayev, 1978 Nurste, 1973 and Galkovski, 1979) posses the improved characteristics, but because of relative complexity are recommended for (WCD) the big diameter. 

TABLE 15.1 Calculation of characteristics vortex generator Type vortex generator Relative sectionf Factor twistn Degree of overlapping S Spiral... 

Korotkov, J. F. and Nikolaev, N. A. Hydrodinamic of the Characteristic of Work Mass Transfer VorticalDeviceswith Tangential Vortex Generator. News High Schools of the USSR, Chemistry and Chemical Technology 1972,5, S00-S04,(inRussian). 

Hydraulic characteristics conic vortex generator type ATVP are most full investigated researched by development high-economical direct-flow cyclones (Kouzov, 1972 and Adamar, 1970). 

The specific surface area of an industrial-sized continuous stirred tank reactor (CSTR) can be calculated from the reactor dimensions. However, it is difficult to estimate the effect of the formation of bubbles and of the stirrer-induced vortex at low melt viscosity. The calculation of the characteristic length of diffusion in a high-viscosity finishing reactor with devices for the generation of thin films with respective high specific surface areas is more complex. 

The reciprocating motion of the sieve plate generates vortices in the biosuspension. Each vortex region represents the elementary volume of the bioreactor. When the gas dispersion element moves upwards, the biosuspension is forced to pass through the holes of the sieve plates From each hole, a jet of biosuspension flows downward into the space between two sieve plates. The jet reverses direction as the element reverses direction. Very effective dispersive action is due to the periodic generation of bubbles, which renews the larger interfacial area on each reversal of direction. The important design characteristics of this reactor are summarized in Table XXV. 

Hydrocyclones, also called hydroclones, employ self-generated mild centrifugal forces to separate the particles into groups of predominantly small and predominantly large ones. Because of bypassing, the split of sizes is not sharp. The characteristic diameter of the product is taken as rfso, the diameter than which 50 wt % of the material is greater or less. The key elements of a hydrocyclone are identified on Figure 12.3(h). A typical commercial unit has an inlet area about 1% of the cross-sectional area between the vessel wall and the vortex finder, a vortex finder with diameter 35 40% that of the vessel, and an apex diameter not less than 25% that of the vortex finder. For such a unit, the equation for the cut point is... 

The frequency of vortex shedding (/) is proportional to the product of the Strouhal number (Ast) and the diameter of the wire dw) or some other characteristic dimension of the object used to generate the vortices and is inversely proportional to the fluid velocity ( /) ... 

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