Jetting region

Between the nonbuoyant jet region and the plume region lies an intermediate region in which the flow changes from the former to the latter.The axial location of the beginning of this intermediate region depends primarily on the exit Froude number ... 

An alternative simple model for contaminant dilution of rooftop exhaust stacks is presented in Halitsky. This model combines a jet region specification for the upward exhaust movement with a more traditional Gaussian plume region controlled by atmospheric and building-generated turbulent dilution. 

In most commercial fluidized bed processes, the bed is much higher than the jet penetration length. There are several parameters that affect attrition in the jetting region, namely the design parameters of the distributor (i.e., orifice diameter, dor, open surface area, Aa, number of orifices, Nor) and the operating parameters (i.e., gas density, pg, volumetric flow rate, vg, superficial gas velocity, t/g, orifice velocity, uor). It holds... 

Assuming there is no interaction between the individual jets, the entire attrition in the jet region can be interpreted as the sum of the contributions of the individual jets. The overall attrition rate of the distributor, Radistr, may thus be related to the jet attrition rate, R... 

Ghadiri, M., Cleaver, J. A. S., and Tuponogov, V. G., Modelling Attrition Rates in the Jetting Region of a Fluidized Bed, Preprint Symposium Attrition and Wear, Utrecht (1992b)... 

Fig. 4. Mass transfer from an impinging jet electrode. (From ref. 48 by permission of the publisher, The Electrochemical Society, Inc.). I, Potential core region II, established flow region III, stagnation region IV, wall-jet region.

The spouting vessel is conunonly either cylindrical or conical in shape (Fig. 2). With the former it is preferable to have a short conical base tapering down to the inlet orifice, so that the solids in the annulus can easily slide into the gas jet region without forming any dead zone at the base. Most of the work outside the Soviet Union has been carried out in this type of vessel, while spouting in conical vessels has received particular attention in the Soviet Union, and has been extensively discussed in a book by Romankov and Rashkovskaya (R4). The general discussion of spouted bed behavior in this review is in the context of a cylindrical column. 

Silverman [21] derived velocity correlations between a rotating cylinder (mO, pipe flow (m2), annulus flow (1/3), and an impinging jet (wall jet region only, 1/4), as listed in Table 2. These equations assume that the appropriate transformations are to be made on the basis of equal mass-transfer rates for the different geometries. Silverman [21] also explored the case where the equality of surface shear stress is the appropriate criterion, on the basis that the equality of the shear stress will ensure the same corrosion processes for the various geometries. We stress that the equations listed in Table 2 must be used with great caution because they are based on the... 

The NMGBF has similarities to two filter types the spouted bed and the fluidised bed filter. Geometrically the NMGBF is a spouted bed with a draft tube in the central spout jet region as shown in Figure 3. 

The matrix of overall mass transfer coefficients for the jetting region is, therefore... 

The comparison between confined and unconfined results for Swirler 504545 shows the significant effect of the confining tube on the swirling flow in terms of jet expansion and decay rate, enlargement of the CTRZ, and reduced turbulent intensity which becomes more uniform in the center jet region. This fact emphasizes the importance of the expansion ratio at the combustor inlet. 

You, H.-Z. "An Investigation of Fire-Plume Impingement on a Horizontal Gelling 2—Impingement and Ceiling-Jet Regions." Fire Materials 9, no. L (1985) 46-56. 

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