Mixing turbulent flow

Deutsch-Anderson equation assumes no reentrainment from collector well mixed turbulent flow, turbulent eddies small compared to precipitator dimensions... 

The time-to-distance transfonnation requires fast mixing and a known flow profile, ideally a turbulent flow with a well-defined homogeneous composition perpendicular to the direction of flow ( plug-flow ), as indicated by tire shaded area in figure B2.5.1. More complicated profiles may require numerical transfomiations. 

Flow in tubular reactors can be laminar, as with viscous fluids in small-diameter tubes, and greatly deviate from ideal plug-flow behavior, or turbulent, as with gases, and consequently closer to the ideal (Fig. 2). Turbulent flow generally is preferred to laminar flow, because mixing and heat transfer... 

In turbulent flow, axial mixing is usually described in terms of turbulent diffusion or dispersion coefficients, from which cumulative residence time distribution functions can be computed. Davies (Turbulence Phenomena, Academic, New York, 1972, p. 93), gives Di = l.OlvRe for the longitudinal dispersion coefficient. Levenspiel (Chemical Reaction Engineering, 2d ed., Wiley, New York, 1972, pp. 253-278) discusses the relations among various residence time distribution functions, and the relation between dispersion coefficient and residence time distribution. 

Turbulent flow, by means of the chaotic eddy motion associated with velocity fluctuation, is conducive to rapid mixing and, therefore, is the preferred flow regime for mixing. Laminar mixing is carried out when high viscosity makes turbulent flow impractical. 

As in the case of turbulent flow, then, smaU-diameter impellers (D < Df/3) are useful for (1) rapid mixing of diyparticles into hquids,... 

FRP, plastics (polyvinyl chloride, polyethylene, polypropylene, and other similar materials), and rubber are general use and are recommended for alum solutions. Care must be taken to provide adequate support for these piping systems, with close attention given to spans between supports so that objectionable deflection will not be experienced. The alum solution should be injected into a zone of rapid mixing or turbulent flow. 

Mixing rate constants for fully turbulent flow regimes (Npg > 10,000)... 

In either laminar or turbulent flow, rotational eireulation of a proeessed material around its own hydraulie eenter in eaeh ehannel of the mixer eauses radial mixing of the material. All proeessed material is eontinuously and eompletely intermixed, virmally eliminating radial gradients in temperature, veloeity, and material eomposition. 

Stark, S. V. 19.50. Submerged turbulent flows mixing. Ph.D. thesis. Moscow Institute ot Sreei and Alloys (MISiS). 

German guidelines base the division on the resulting airflow pattern within the room rather than distribution methods. They suggest that airflow patterns be divided into four categories hall-filling mixed flow zonewise mixed flow low-momentum, low-turbulence flow for the air supply in the work region and zonewise displacement ventilation. 

In most cases, laminar gas flow is an unrealistic assumption. A more realistic alternative is to assume a complete mixing of air in the collection system. The collection efficiency in the case of turbulent flow tj j- is given by... 

Further details ean be found in texts eoneerning fluid mixing and partiele suspension (Sterbacek and Tausk, 1965 Holland and Chapman, 1966 Oldshue, 1983 Uhl and Gray, 1986 Allen, 1990 Coulson and Riehardson, 1991 Harnby etal., 1992 and Gibilaro, 2001), the theory partieulate of proeesses (Randolph and Larson, 1988 Ramkrishna, 2000) and turbulent flows (Pope, 2000). 

The better mixing occurs under turbulent flow conditions. 

Correlating factor for viscous flow power, Table 5-1 Mixing factors, turbulent flow power. Table 5-1 Viscosity correction factor for turbulent How (static mixer)... 

General laws for the flow of fluids were determined by Reynolds, who recognized two flow patterns, laminar and turbulent. In laminar flow the fluid can be considered as a series of parallel strata, each moving at its own speed, and not mixing. Strata adjacent to walls of the duct will be slowed by friction and will move slowest, while those remote from the walls will move fastest. In turbulent flow there is a general forward movement together with irregular transfer between strata. 

Hie problem associated with poor mixing in a large vessel was identified as low dissolved oxygen in the aerated vessel. The mixing time has been correlated with turbulent flow. In... 

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