Ligament disintegration

Droplet Formation in Centrifugal Atomization. The mechanisms of centrifugal atomization of liquid metals are quite similar to those for normal liquids. Three atomization modes have been identified in rotating electrode atomization process, i.e., (I) Direct Droplet Formation, (2) Ligament Disintegration, and (3) Film/Sheet Disintegration.1[189][32°] are aiso applicable to the centrifugal atomiza-... 

Figure 4.3. Regimes in centrifugal atomization of melts Direct Droplet Formation, Ligament Disintegration, and Film/Sheet Disintegration.

The disintegration of liquid sheets as studied by many authors [40-42] is generally a two-step process. First, liquid threads and/or ligaments disintegrate from the sheet, which secondly break into droplets due to capillary instabilities. This can be induced either through perforations or destabilising waves in the liquid sheet [40]. 

Disintegration of Ligaments into Primary Membranous Fragments and Spheroid Droplets... 

In both atomization modes, as thin unstable ligaments, and/ or sheets disintegrate into round droplets, atomization gas may plausibly be trapped into the droplets under certain conditions. For alloys with alloying elements which readily react with atomization gas, for example, oxidize to form refractory oxides, solidification may be delayed and spheroidization is prevented so that rough flakes may form. For such alloys, the atmosphere in the spray chamber must be inert and protective to avoid the formation of any refractory and to foster spheroidal shape of droplets. 

Hollow-Cone Sprays. In swid atomizers, the liquid emerges from the exit orifice in the form of a conical sheet. As the liquid sheet spreads radially outward, aerodynamic instability immediately takes place and leads to the formation of waves which subsequently disintegrate into ligaments and droplets. Figure 3 illustrates the breakup process in an annular liquid sheet. 

It is commonly accepted that there are three disintegration regimes for liquids discharged from a rotating disk, namely direct drop, ligament, and sheet formation - (Figure 6.3). 

Abstract This chapter relates to the liquid sheets and their instabihty. Liquid sheet instability is due to the interaction between the hquid and its surrounding fluid. When the amplitude of a perturbation grows and reaches a critical value, sheet is disintegrated forming liquid ligaments. Here, the linear and nonlinear instability of an inviscid and viscous liquid sheet is discussed, showing the effect of the aerodynamic forces on the growth rate of the initially small perturbations. Other effects, such as the effect of initial velocity profile on the instability are also discussed. 

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