Vortex inner/outer

A positive value iadicates vertical movement. Thea, moving from the outer wall to the air core, the axial velocity iacreases to positive values. Thus, the fluid motioa is dowa the wall of the cycloae to the apex and up the air core through the vortex finder. In the cylindrical section, the axial velocity goes negative again, approaching the vortex-finder wall. The fluid flow is then down the inner cyclone wall and the outer vortex-finder wall. There is a locus of zero axial velocity. 

This is most easily achieved by rotating the inner cylinder and keeping the outer fixed in the laboratory frame. Note, however, that this geometry leads to the formation of Taylor vortex motion if inertial effects become important (Reynolds number Re 1). Most rheo-NMR experiments are actually performed at low Re. In the cylindrical Couette, the natural coordinates are cylindrical polar (q, <(>, z) so the shear stress is denoted and is radially dependent as q 2. The strain rate across the gap is given by [2]... 

The vortex flow reactor was a glass Couette cell driven by a Bruker RheoNMR system. The cell consisted of a stationary outer glass tube with an id of 9 mm and a rotating inner glass tube with an od of 5 mm, giving a gap of 2 mm. The Couette was filled with cylindrical bacterial cells, F. nucleatum ( 2 x 20 pm), suspended in water at a concentration of =10" cells mL-1. 

As illustrated in Fig. 5, the outer downwardly spiralling gas velocity decays as gas peels off into the inner upwardly spiralling exiting vortex. The length of this inner vortex, the natural vortex length, L, (Alexander, 1949) then represents the distance below the edge of the gas outlet tube below which no feed gas remains to peel off into the inner vortex. If the... 

The inner vortex (often called the core of the vortex) rotates at a much higher velocity than the outer vortex. In the absence of solids, the radius of this inner vortex has been measured to be 0.4 to 0.8 r. With axial inlet cyclones, the inner core vortex is aligned with the axis of the gas outlet tube. With tangential or volute cyclone inlets, however, the vortex is not exactly aligned with the axis. The non-symmetric entry of the tangential or volute inlet causes the axis of the vortex to be slightly eccentric from the axis of the cyclone. This means that the bottom of the vortex is displaced some distance from the axis and can "pluck off and reentrain dust from the solids... 

This means that the separating ability of the inner vortex is 8 times that of the outer one. 

If Po is the radial distance of the inner vortex, and Ri that of the outer one, then according to Lissman we may put Po = V2P1 (approx.) so that... 

Figure 12 Experimental set-up of Taylor vortex photocatalytic reactor (Dutta and Ray, 2004) (1) motor, (2) speed controller, (3) gear coupling, (4) UV lamp, (5) sample collection point, (6) lamp holder, (7) outer cylinder, (8) catalyst-coated inner cylinder.

As an alternative to a cascade of CSTR trains, a novel continuous reactor with a Couette-Taylor vortex flow (CTVF) has been proposed, which can realize any flow pattern between plug and perfectly mixed flows [361-366]. A continuous Couette-Taylor vortex flow reactor (CCTVFR) consists of two concentric cylinders with the inner cylinder rotating and with the outer cylinder at rest. Figure 29 shows a typical flow pattern caused by the rotation of the inner cylinder. 

The effect of polymer solutions, ejected at very small flow rates at the tip of a finite span hydrofoil, on the inception and extent of tip vortex cavitation is investigated. The results show that the dessinent cavitation numbers are significantly reduced by polymer additives as compared with those in pure water. Moreover, for operating conditions well below critical, the presence of polymer in the vortex core results in the nearly complete elimination of the vapour cavity. These effects can be interpreted on the basis of a modification of the velocity field due to the viscoelastic properties of the polymer solutions. L.D.A. measurements indicate a large decrease of the tangential velocity component in the transition region between the inner solid body rotation co.e and the outer potential vortex flow. Also, a change of the slope of the velocity within the core is observed. 

The flow of a fluid through an elbow resembles free vortex motion, the product of the local flow velocity, bend radius remains constant, and there is a well-defined pressure gradient along the radius of curvature of the elbow. One can relate these pressure gradients to the flowrate through the elbow, and the measurement of the pressure difference between the inside and the outside of the elbow can be used to determine the volumetric flow rate of a fluid through the elbow. The first use of elbow as flowmeter was reported by Jacobs and Sooy [15]. They found that the inner and outer pressure difference (Ah) was related to the average velocity as... 

In the Messo turbulence crystallizer, a secondary circulation loop (see vortex) -driven by the primary circulation loop - is created in the outer suspension section. This secondary circulation loop serves the purpose of sorting out the coarser crystals from the inner draft tube recirculation process, concentrating them in an outer... 

---