Vortex cross

VoHex shedding The vortex-shedding frequency of the fluid in cross-flow over the tubes may coincide with a natural frequency of the tubes and excite large resonant vibration amplitudes. 

Acoustic Coupling When the shell-side fluid is a low-density gas, acoustic resonance or coupling develops when the standing waves in the shell are in phase with vortex shedding from the tubes. The standing waves are perpendicular to the axis of the tubes and to the direction of cross-flow. Damage to the tubes is rare. However, the noise can be extremely painful. 

Figure 30. Cross-sectional view of a double-vortex spray chamber.

The unit shown in Figure 4-49 has been used in many process applications with a variety of modifications [18,19,20]. It is effective in liquid entrainment separation, but is not recommended for solid particles due to the arrangement of the bottom and outlet. The flat bottom plate serves as a protection to the developing liquid surface below. This prevents re-entrainment. In place of the plate a vortex breaker type using vertical cross plates of 4-inch to 12-inch depth also is used, (Also see Reference [58].) The inlet gas connection is placed above the outlet dip pipe by maintaining dimension of only a few inches at point 4. In this type unit some liquid will creep up the walls as the inlet velocity increases. 

Liquid Surfoee Protection Plote, Mop be Perforoted.lf Cross-Plote Vortex Breoker Used in Piece of riot Plote Piece so Portion is Both in end out of Liquid Level. 

The cross-flow or tangential fan sets up an eccentric vortex within the fan runner, the air coming inwards through the blades on one side and leaving outwards through the blades on the other. It can, within mechanical limits, be made as long as necessary for the particular duty. 

Schlieren image of a tulip flame and the remnants of the vortex, proposed to initiate the instability. The tube is acrylic with square cross section of 38.1mm on the side. The mixture is stoichiometric methane/air. 

Of much greater relevance in micro reactors are rectangular channels, which were the subject of a study by Cheng et al. [110], among others. They solved the Navier-Stokes equation for channel cross-sections with an aspect ratio between 0.5 and 5 and Dean numbers between 5 and 715 using a finite-difference method. The vortex patterns obtained as a result of their computations are depicted in Figure 2.20 for two different Dean numbers. 

Dp Particle diameter Dth Smallest particle able to cross width Lw El Collection efficiency at actual inlet loading E0 Collection efficiency at <1 gr/ft3 inlet loading H Cyclone height as defined in Fig. 6 L Natural Vortex Length... 

Mix Vortex if possible.Vortexing is gentle, simple to perform and eliminates cross contamination Z620 Vortex Station... 

Fig. 21a-d. Flow from startup into a 4 1 contraction computed for the pom-pom model with fixed total and cross-bar molecular weight and Weissenberg number (dimensionless deformation rate) of 3[(a) and (b)] and 8 [(c) and (d)]. (a) and (c) show (colour coded) the level of dimensionless stretch of the pom-pom cross-bar, X. (b) and (c) show the respective streamlines. Note the spur of preoriented material joining the wall to the funnel and the reduction of the corner vortex at high flow rates when extension thinning sets in. (Computations courtesy of Dr. T. M. Nicholson)... 

Depending on the particular jet initial conditions, several or no axis rotations can occur in the first few diameters of jet development (e.g., [3, 16]). Results of experiments, stability analysis, and simulations support the concept that the basic mechanism for the first axis rotation of the jet cross-section is the selfdeformation of the vortex rings due to nonuniform azimuthal curvature at the... 

Bhaga (B3) determined the fluid motion in wakes using hydrogen bubble tracers. Closed wakes were shown to contain a toroidal vortex with its core in the horizontal plane where the wake has its widest cross section. The core diameter is about 70% of the maximum wake diameter, similar to a Hill s spherical vortex. When the base of the fluid particle is indented, the toroidal motion extends into the indentation. Liquid within the closed wake moves considerably more slowly relative to the drop or bubble than the terminal velocity Uj, If a skirt forms, the basic toroidal motion in the wake is still present (see Fig. 8.5), but the strength of the vortex is reduced. Momentum considerations require that there be a velocity defect behind closed wakes and this accounts for the tail observed by some workers (S5). Crabtree and Bridgwater (C8) and Bhaga (B3) measured the velocity decay and drift in the far wake region. 

Dispcrscd-ga units. In these units, gas bubbles arc dispersed in the total stream either by the use of an inductor device or by a vortex set up by mechanical rotors. Fig. 8 shows schematic cross-section of such a unit. 

The concept of cross-flow velocity is quite important in understanding how heat exchangers work. This concept is related to a flow phenomenon called vortex shedding. Perhaps you have seen a wire quivering in the wind. What causes the wire to vibrate with such energy ... 

To encourage vortex shedding and turbulence on the shell side of a heat exchanger, we must increase the cross-flow velocity. To calculate the cross-flow velocity, we proceed as follows ... 

The baffle cut, shown in Fig. 19.3, is usually about 20 to 30 percent of the diameter of the baffle. The smaller the baffle cut, the more perpendicular the flow across the tubes. Perpendicular flow encourages desirable cross-flow velocity and vortex shedding. But a smaller baffle cut will also increase the pressure drop on the shell side. 

To differentiate a filament from a vortex intrusion case, we use a method based on the evolution of the potential vorticity along the cross-section between the OHP station and the vortex center defined from the PV maximum. 

In the figure 4 and 5, we can see a PV map with a filament over the OHP station and the PV evolution along the cross-section associated with a positive distance and the figures 6 and 7 show the case of the vortex intrusion associated with a negative distance. 

Studies have shown that the retrieval accuracy is particularly sensitive to horizontal temperature gradients. For example, ignoring a temperature gradient of 3 K / 100 km (a typical maximum, e.g. associated with crossing the polar vortex) can lead to composition retrieval errors of tens of %, although these errors are localized and... 

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