Spray hollow-cone

Hollow-Cone Sprays. In swid atomizers, the Hquid emerges from the exit orifice ia the form of a cooical sheet. As the Hquid sheet spreads radially outward, aerodyaamic iastabiHty ioimediately takes place and leads to the formation of waves which subsequently disiategrate iato ligaments and droplets. Figure 3 illustrates the breakup process ia an annular Hquid sheet. 

A hollow-cone spray can be generated via a simplex atomizer. The spray pattern varies depending on the injection pressure. At very low pressures, liquid dribbles from the nozzle orifice. With increasing pressure, the liquid emerges from the orifice as a thin,... 

Solid-cone spray atomizers usually generate relatively coarse droplets. In addition, the droplets in the center of the spray cone are larger than those in the periphery. In contrast, hollow-cone spray atomizers produce finer droplets, and the radial liquid distribution is also preferred for many industrial applications, particularly for combustion applications. However, in a simplex atomizer, the liquid flow rate varies as the square root of the injection pressure. To double the flow rate, a fourfold increase in the injection pressure is... 

An entirely different unstable contactor involves the thin expanding liquid film produced by a hollow cone spray nozzle. Because of fresh surface and the thinness of the film, this can give very high transfer for liquid-limited systems. Two applications are direct contact condensation and removal of volatile components from a high-boiling residual liquid. 

Spray Towers as Direct Contact Condensers Similarly spray contactors can be highly effective for direct contact condensers, which are also liquid-limited. The high transfer rate in the initial formation of sprays is the key. Kunesh [Ind. Engr. Chem. Res., 32, 2387-2389 (1993)f reported a 97 percent approach to equilibrium in a hydrocarbon system in the 6-in space below the discharge of a row of hollow cone spray nozzles. 

Conical sprays can be further broken down into either full-cone or hollow-cone sprays. In the hollow cone pattern all of the spray is located at the surface of the cone produced by the nozzle and none of it is inside the cone. In the full cone pattern the liquid being sprayed fills the cone pattern produced by the nozzle. 

The differences in full- and hollow-cone spray patterns can be seen in Figure 4.5. In this figure the spray flux, gpm/ft2, is plotted versus the radial distance from the center line of the spray nozzle. For the hollow-cone spray there is very little water at the center of the spray. Instead, it is all at the outer edge. Conversely, for the full-cone spray, the water is fairly evenly distributed radially about the center line of the nozzle. 

The fuel emerged from the orifice as a conical liquid sheet and subsequently disintegrated into a conical spray. Delavan atomizers in three different sizes (nominal flow rates of 1, 2, and 5 gph), three different spray angles (45, 60, and 90 degrees) and with hollow cone spray patterns were investigated. Nominal fuel pressures considered were 50, 100, and 150 psig. 

Core-insert cone nozzles prodnce either a solid or hollow cone spray pattern. They operate at moderate pressnres and give a finely atomized spray. They shonld not be used for wettable powders because of small passages which tend to clog and wear rapidly due to abrasion. 

Fig. 4. Three-dimensional distribution of Sautei mean diameter (SMD) in a typical hollow-cone spray.

Moreira ALN, Panao MRO (2006) Heat transfer at multiple-intermittent impacts of a hollow cone spray. International Journal of Heat and Mass Transfer 49 4132-4151. 

Fig. 24.38 The swirl inserts in a swirl nozzle with axial flow, for (a) hollow cone spray, and (b) a full cone spray (Courtesy of Lechler, Inc.)...

W. M. Ren, J. F. Nally Jr., Computations of hollow-cone sprays from a pressure-swirl injector, SAE Technical Paper 982610, Society of Automotive Engineers, Warrendale, 1998. 

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