where A is a constant, dm is in /'m. Vw is in m/s, and n is the number of metal droplets formed from the impact of one water droplet. In this mathematical form, water flow rate, water pressure, momentum and energy, jet length, and metal flow rate are not primary parameters influencing dm; they do, however, affect particle size by influencing water-jet velocities and the number of water droplets. Also, the number of metal droplets produced per water droplet can vary without altering the basic details of the model.

Waler drop

Waler drop

Exploding steam packet

Fig. 7 Impact model of water atomization mechanism. Source: Ref 5

Collisions during atomization can also influence particle size, particle size distributions, and particle shape (Ref 8, 9). Collisions reduce the efficiency of atomization, and the probability of particle collisions increased with increasing metal flow rate. Thus, the maximum of average particle size and geometric standard deviation are achieved in the center of the atomizing stream, where metal concentration generally is highest.

Collisions also cause gas entrapment and microinhomogeneity from internal (primary) particle boundaries. Collisions between particles usually overlap with the earlier stages of atomization. These collisions are minimized or practically eliminated in centrifugal modes of atomization, in which traffic density of the particle decreases rapidly with distance.

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