高圧高速液流の微粒化の研究 第2報

抄録

Continued from the 1st report, we observed the mechanism of laminar flow, turbulent flow and spray of issuing liquid jets by means of ultra-ropid photography. The empirical formula for the jet length of laminar flow is given by [numerical formula]. The transition velocities from laminar to turbulent ν_c and turbulent to sprayν_s are given by the equations [numerical formula], where μ/√(σρD)=stability number andνD/ν=Reynolds' number. The critical Reynolds' number (ν_cD/ν) of liquid with high stability number is smaller than the one with low stability number, i.e. the critical Reynolds' number of heavy oil is smaller than that of water. But the jet length of the heary oil is much longer than the water. The reason is that the jet length is nearly proportional to the issuing velocity ν, which takes a larger value for the larger kinematic viscosity ν. The spraying phenomena of viscous liquid has the so-called starting length. Near the nozzle, the flow is laminar. Apart from it, the flow becomes turbulent. Far from it, the flow spreads by the surface friction with air accompanying the thin liquid films.