Flow Patterns in Pipes

Plug flow A simple convective flow pattern in pipes and tubes that is characterized by a fluid velocity independent of radial position, complete mixing in the radial direction, and no mixing in the axial direction. Also called the parallel tube model or tubular flow. See Eqs. (7) and (8) and Figure 3. 

Reynolds number and flow patterns in pipes and tubes... 

As mentioned in Chapter 1, the first published work on fluid flow patterns in pipes and tubes was done by Reynolds in 1883. He observed the flow patterns of fluids in cylindrical tubes by injecting dye into the moving stream. Reynolds correlated his data by using a dimensionless group later known as the Reynolds number Re ... 

Fig. 4. 68 Flow patterns in pipes of different contact angles...

FIG. 6-24 Gas/liqi lid flow patterns in horizontal pipes. From Alves, Chem. Eng. Progr., 50, 449 56 [1.9.54].)... 

Rhodes, and Scott Can. j. Chem. Eng., 47,445 53 [1969]) and Aka-gawa, Sakaguchi, and Ueda Bull JSME, 14, 564-571 [1971]). Correlations for flow patterns in downflow in vertical pipe are given by Oshinowo and Charles Can. ]. Chem. Eng., 52, 25-35 [1974]) and Barnea, Shoham, and Taitel Chem. Eng. Sci, 37, 741-744 [1982]). Use of drift flux theoiy for void fraction modeling in downflow is presented by Clark anci Flemmer Chem. Eng. Set., 39, 170-173 [1984]). Downward inclined two-phase flow data and modeling are given by Barnea, Shoham, and Taitel Chem. Eng. Set., 37, 735-740 [1982]). Data for downflow in helically coiled tubes are presented by Casper Chem. Ins. Tech., 42, 349-354 [1970]). 

Figure 23. Flow patterns in vertical pipe flow.

Dukler, A. E. and Taitel, Y, Flow Patterns in Horizontal and Near Florizontal Pipes, Design Manual FM-3, DIMP/AIChE, New York, 1982 also see Design Manual WFP/AlChE, same reference. 

Weisman, J., Duncan, D Gibson, J. and Crawford, T. Inti. JL Multiphase Flow 5 (1979) 437-462. Effects of fluid properties and pipe diameter on two phase flow patterns in horizontal lines. 

Barnea D, Luniski Y, Taitel Y (1983) Flow pattern in horizontal and vertical two phase flow in small diameter pipes. Can J Chem Eng 61 617-620 Baroczy CJ (1963) Correlation of liquid fraction in two-phase flow with application to liquid metals, NAA-SR-8171. Butterworth, London... 

Figures 3.1a and 3.16 show the flow patterns in vertical and horizontal pipes, respectively. Obviously, stratified flow does not exist in vertical flow, because of the relative direction of the flow and gravitational force, and a more symmetrical flow pattern is possible in vertical flow than in horizontal flow. Flow patterns identified in the figure can be described as follows.

Figure 3.61 Critical flow patterns in a short pipe. (From Zaloudek, 1963. Reprinted with permission of U.S. Department of Energy, Washington, DC, subject to the disclaimer of liability for inaccuracy and lack of usefulness printed in cited reference.)...

Barnea, D., Y. Luninski, and Y. Taitel, 1983, Flow Pattern in Horizontal and Vertical Two-Phase Flow in Small Diameter Pipes, Can. J. Chem. Eng. 67 617-620. (3)... 

The flow patterns in liquid-liquid systems have not been as extensively studied as those in gas-liquid systems. However, Russell et al. (R6), and Charles et al. (C3) have studied the flow of oils and water in horizontal pipes and have presented flow-pattern charts for the various oil-water systems. It is very difficult to predict the flow pattern for a liquid-liquid system, unless the liquids have physical properties similar to those of water and the oils used by Govier and co-workers. The Baker chart might be used to give a first estimate of the flow pattern for a liquid-liquid system, but the viscosity of the less-dense phase is not included in the coordinate parameters, and the feasibility of such an approach has never been investigated. 

Govier et al. (G5, G6, B14) have correlated flow patterns in terms of the location of the two minima and the maximum observed in the pressure drop vs. gas-liquid volumetric feed ratio (12 ) curves (cf. Fig. 2). Gas-liquid ratios, gas flow, liquid flow, pipe diameter and gas-phase density were investigated for the air-water system in isothermal flow. From the correlations presented (as against a function, when n varies... 

Akagawa, Sakaguchi, and Ueda (Bull JSME, 14, 564-571 [1971]). Correlations for flow patterns in downflow in vertical pipe are given by Oshinowo and Charles (Can. J. Chem. Eng., 52,25-35 [1974]) and Barnea, Shoham, and Taitel (Chem. Eng. Sci., 37, 741—744 [1982]). Use of drift flux theory for void fraction modeling in downflow is... 

The flow pattern in a horizontal gas-solid pipe flow varies with the solids concentration. In a horizontal pipe flow at a given gas flow rate, the following flow patterns sequentially occur as the particle loading, defined as the mass flow ratio of particles to gas, increases ... 

Oyama and Aiba (O10) observed the mean flow patterns in a mixing tank by use of a small rotating pointer, similar to a weather vane, suspended at the end of a pipe at different locations in the vessel. Their studies on two-blade flat paddles in an unbaffled cylindrical vessel confirm the expected presence of a vortex, deepening with speed of rotation, and of swirling flow about the tank axis with a slight amount of flow up the tank walls and down in the center. 

The enhancement in the bed-wall heat transfer coefficients in bubble columns as well as the two- and three-phase contactors as compared to the single phase pipe flow is likely because of the strong circulation flow pattern in the continuous phase. 

FLOW PATTERNS IN COMPRESSIBLE FLOW IN A PIPE (Subsonic, Sonic Supersonic). 

Disadvantages Natural solid sump in bottom, Boilout cycles are usually frequent. Internal down-pipe may plug. Difficult to model and scale-up. Flow patterns in suspension chamber not uniform. 

Pipe Flow. The rheological properties of cement slurries have also been characterized using pipe viscometers (13,15-18). The experimental results show different flow patterns. In some circumstances, relatively large pipe diameters and high shear rates, the flow curves, and shear-stress at the wall versus Newtonian shear rate at the wall are independent of pipe diameter (16, 17). The reverse situation is observed when pipe diameters are relatively small, of the order of 5 mm (13, 15). The diameter dependency of the flow curves can be explained, as discussed... 

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