Longitudinal flow

Metal contained in the channel is subjected to forces that result from the interaction between the electromagnetic field and the electric current in the channel. These inward forces produce a circulation that is generally perpendicular to the length of the channel. It has been found that shaping the channels of a twin coil inductor shown in Figure 10 produces a longitudinal flow within the channel and significantly reduces the temperature difference between the channel and the hearth (12). 

In all of these configurations, maintaining longitudinal flow on both the shellside and tubeside allows the decision for placement of a fluid stream on either one side or the other to be based upon design efficiency (mass flow rates, fluid properties, pressure drops, and veloci-... 

Vortex formation leads to a considerable drop in mixing efficiency and should be suppressed as much as possible in practical applications to increase the homogenizing effects of mixers. The preferable method of vortex suppression is to install vertical baffles at the walls of the mixing tank. These impede rotational flow without interfering with the radial or longitudinal flow. Figure 11 illustrates such a system. 

Calculate loss due to longitudinal flow through tube bundle use Figure 10-141. 

Figure 10-141. Pressure drop in exchanger shell due to longitudinal flow. (Used by permission Buthod, A. P. Oil Gas Journal, V. 58, No. 3, 1960. PennWell Publishing Company. All rights reserved.)...

For longitudinal flow in the tubes of shell boilers the mean heat transfer coefficient may be determined from ... 

Though experimental data on suspensions of fibers in Newtonian dispersion media give more or less regular picture, a transition to non-Newtonian viscoelastic liquids, as Metzner noted [21], makes the whole picture far or less clear. Probably, the possibility to make somewhat general conclusions on a longitudinal flow of suspensions in polymer melts requires first of all establishing clear rules of behavior of pure melts at uniaxial extension this problem by itself has no solution as yet. 

The most common technique for the measurement of k(T) at low temperatures is the steady longitudinal flow method a steady thermal power flow along a sample of section A (i.e. a cylinder or a bar) is produced by a temperature gradient AT. If the power flows only in the x direction, eq. (11.1) becomes ... 

Figure 13.13 shows such a distribution measured by Menges and Wiibken (30) for amorphous PS. They measured the shrinkage of microtomed molded samples at elevated temperatures. Figure 13.13(a) shows the longitudinal (flow direction) orientation distribution at two injection rates. The characteristic features of the orientation distribution are a maximum orientation at the wall that vanishes at the center with a local maximum near the wall. In Fig. 13.13(b), the longitudinal orientation at the wall and secondary maximum orientation are in close proximity, and the transverse orientation drops continuously from a maximum value at the surface. 

Longitudinal Flow Baffles In fixed-tube-sheet construction... 

The boundary conditions that will be adopted at y = 0 (where conditions will be identified by the subscript 0) are = 0,(Xp = (Xp q = constant (a measure of the sublimation or boiling temperature), and u = 0. The first of these conditions would follow from a flame-sheet hypothesis and is accurate for many liquid fuels (see Section 3.3.4 or [21]). The validity of the second condition is discussed in Section 3.3.4 this condition will be most accurate for a volatile liquid fuel. The third condition is rigorously true only for a solid fuel but is an excellent approximation for liquid fuels if longitudinal flow of the liquid is surpressed (for example, by extruding the liquid through a porous solid material). ... 

More recently, the cross-flow filtration combustion configuration (Fig. 29), commonly used for powder production, was investigated (Dandekar et al., 1990). Within the reactor, a rectangular container holds the solid reactant powder, and the gaseous reactant is transported from the surroundings to the front not only by longitudinal flow from above, but also by countercurrent flow from ahead of the front. The assumptions used in the model were as follows ... 

Lift Forces Combined with the Field Action. The hydrodynamic lift forces that appear at high flow rates of the carrier liquid combined with the primary field are able to concentrate the hard suspended particles into the focused layers. The retention behavior of the particles under the simultaneous effect of the primary field and lift forces generated by the high longitudinal flow rate can vary with the nature of various applied primary field forces. 

As was mentioned in Section I, heat transport phenomena of longitudinal flow through rod bundles (i.e., transport from the rods to the fluid v.v.) have been studied quite extensively in the past and are still receiving constant attention, due to the importance of compact heat exchangers and nuclear reactors. This has led to many theoretical and empirical relations to predict Nusselt numbers as a function of the relative pitch and (for nonlaminar flow) the Reynolds number a relatively recent review of those relations that pertain to smooth rod bundles is by Rehme [6]. 

K. Johannsen. Longitudinal flow over tube bundles, Low Reynolds Number Flow Heat Exchangers (S. Kaka, R.K. Shah, and A.E. Bergles, eds.). Hemisphere, Washington, 1983, p. 229. 

P.N. PustyPnik, B.F Bulunov, and Blagoveshchenskii. A.Y, Heal transfer with forced longitudinal flow of air through a bundle of tubes with boundary condition Tw const. Thermal Engineering J7 135 (1990). 

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