Measurements of drop size distributions have been obtained by photogra
phy for air-water annular flow in a 4.2 cm vertical pipe. Results are
presented for a constant superficial gas velocity (36 m/s) for differe
nt liquid flows. It is shown that droplet deposition rates can be inte
rpreted by relating the deposition constant directly to the root-mean
square of the velocity fluctuations of the drops. The observed decreas
e of the deposition constant with increasing liquid flow cannot be exp
lained by an increase in drop size. It is suggested that droplet-dropl
et interactions cause a decrease in drop turbulence. Copyright (C) 199
6 Elsevier Science Ltd.