Concentric jets

Troyanovsky, V. N. 1969. Studies of the Allowable Initial Air Temperature Difference of the Ambient Air and Air Supplied by the Ventilation System with Concentrated jets. Research Report T-5-69. KazIOT, Kazan. 

The room airflows are controlled mainly by the supply or/ md circulation air jets using, for example, concentrated jets, ceiling air supply, or high-impulse nozzle systems. Examples of different methods are illustrated in Fig. 8.14. 

For concentric jets and gas-solid two-phase jets, the jet momentum flux term pf(73 can be evaluated as follows, as suggested by Yang et al. (1984b) ... 

The solids particle velocity in the gas-solid two-phase jet can be calculated as shown in Eq. (27), assuming that the slip velocity between the gas and the solid particles equals the terminal velocity of a single particle. It should be noted that calculation of jet momentum flux by Eq. (26) for concentric jets and for gas-solid two-phase jets is only an approximation. It involves an implicit assumption that the momentum transfer between the concentric jets is very fast, essentially complete at the jet nozzle. This assumption seems to work out fine. No further refinement is necessary at this time. For a high velocity ratio between the concentric jets, some modification may be necessary. 

Figure 37. Effect of solids loading on gas mixing among concentric jets—tracer injected via air tube at air tube gas velocity of 31 m/s.

Annular jet. This technology was developed by the Southwest Research Institute and has not been extensively used in the food industry (10). It relies upon two concentric jets. The inner jet contains the liquid core material. The outer jet contains the liquid wall material, generally molten, that solidifies upon exiting the jet. This dual fluid stream breaks into droplets much as water does upon exiting a spray nozzle ... 

Concentric Jet Pump Forward Jetting Sand Bridge... 

The discovery of these new elements by Swedes demonstrated the strides mineralogy was making in that nation. Cronstedt, for instance, introduced the blowpipe into the study of minerals. (See Figure 6.) This was a long, narrowing tube which, when blown into at the wide end, produced a concentrated jet of air at the narrow end. This jet, directed into a flame, increased its heat. 

In co-extrusion, two concentric jets are used (i.e., double fluid nozzle) (Schlameus, 1995 Gouin, 2004) ... 

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