Tangential annular flow

Laser Doppler Velocimetry measurements were performed on a TARS in a cold-flow test rig that simulates an identical hot combustion rig. Axial and tangential velocity mapping of the flow in different cross-sectional planes and along a centerline streamwise plane revealed several important flow structures in the triple annular swirling flow with co-swirling and counter-swirling cases. An axisym-metric recirculation zone was formed in the center of the flow, but the outer... 

Fig. 5 Schematic diagram of tangential generalized annular Couette flow, (a) Geometry for concentric cylinder model (b) typical velocity profiles under varying flow conditions.

As the annular flow models have complex solutions in some cases, they may be approximated by flows in an equivalent parallel-plate geometry (where the gap B between the parallel plates corresponds to the diflerence in cylinder radii). The width W of the parallel plates corresponds to the mean circumference of the cylinders (in the axial flow case) and to the length of the cylinders (in the tangential flow case). Worth [14] has provided flow-rate solutions for the equivalent parallel-plate geometries in the following four simple flow situations ... 

The SDF, like the RTD functions, can be calculated from the velocity distribution in the system that is, a certain flow pattern determines both functions. The reverse, however, does not necessarily apply. The calculation of the SDF requires a complete description of the flow pattern, whereas RTD functions often can be calculated from a less than complete flow pattern. For example, the RTD of axial annular flow between two rotating concentric cylinders (helical flow) of a Newtonian fluid depends only on the axial velocity, whereas the SDF depends on both the axial and the tangential velocity... 

PSA units using adsorbent sheets have been operated by Questair Industries, Inc.46,47,53-55 The sheets were coated with a fine powder of zeolite particles (1-10/rm) and there were spacers between the sheets to establish flow channels in a flow direction tangential to the sheets and between adjacent pairs of sheets. The sheets could be made in various configurations (rectangular, annular stack, spiral-wound, etc.) and included a support for the adsorbent in the form of an aluminum foil, a metallic mesh, or a matrix that could be woven, nonwoven, ceramic, or wool. These structured materials did not fluidize at high gas velocities and exhibited equilibrium and mass transfer properties of the powdered adsorbent. 

With other short-time dryers, the product motion is in the form of a vortex flow driven by the hot gas which increases the residence time. This can be achieved with hot gas jets tangentially entering the drying area (vortex flow dryers such as helical flow tube with nozzles and annular flow dryer [5.77]), with displacement internals including gas guide vanes (spiral tube pneumatic dryer [5.78, 5.79]), or with tapered inclined perforated screen (cyclone dryer [5.80]). The convex dryer [5.81, 5.82] combines the functions of drying and classifying. With a... 

This standard test method specifies the use of a small-scale apparatus to assess the noncombustibility behavior of budding construction materials under the test conditions. The standard test apparatus consists of two concentric, vertical refractory tubes, 76-mm and 102-mm (3 and 4-in.) in inside diameter and 210 to 250-mm (8.5-10-in.) in length. Electric heating coils outside the larger tube are used to apply heat. A controlled flow of air is admitted tangentially near the top of the annular space between the tubes and passes to the bottom of the inner tube. The top of the inner tube is covered. Temperatures are measured by thermocouples at the center (1) between the two concentric tubes, (2) close to specimen location, and (3) sample surface. 

Substituting Eqns (c) and (e) into Eqn (a), we can determine the rate of entropy production for the tangential annular flow. 

As illustrated in Figure 10.7, a cyclone consists of a vertical cylinder with a conical bottom, a tangential inlet near the top, and outlets at the top and the bottom, respectively. The top outlet pipe protrudes into the conical part of the cyclone in order to produce a vortex when a dust-laden gas (normally air) is pumped tangentially into the cyclone body. Such a vortex develops centrifugal force and, because the particles are much denser than the gas, they are projected outward to the wall flowing downward in a thin layer along this in a helical path. They are eventually collected at the bottom of the cyclone and separated. The inlet gas stream flows downward in an annular vortex, reverses itself as it finds a reduction in the rotation space due to the conical shape, creates an upward inner vortex in the center of the cyclone, and then exits through the top of the cyclone. In an ideal operation in the upward flow... 

Consider now the problem of tangential Newtonian flow in annuli. Suppose one is interested in studying the velocity profiles of an isothermal, incompressible viscous fluid in the annular space between two cylinders, with either one or both cylinders rotating (Figure 7.9). Then, following the literature [31]... 

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