PROPOSAL OF NEW COEFFICIENT INDICATING GENERATION OF AIR-ENTRAINING VORTICES

This paper describes air-entraining vortices generated when water is d rained from a vessel. The liquid used in this experiment is a mixture of water and bentonite. By changing the mixing ratio, the coefficients of kinematic viscosity of the liquid were changed to six values rangi ng from 0.010 5 to 0.062 5 cm(2)/s. Air-core vortices and vortices wit hout air core are not generated in liquid deeper than a certain depth. Within the scope of this experiment, this depth increased with the in crease of flow quantity. Also, it was found that vortices were not gen erated at radial Reynolds number R(r), derived from the equation of mo tion, lower than a certain value. For example, in liquids having the c oefficients of kinematic viscosity upsilon = 0.0105 and 0.0652 cm(2)/s , air-entrained vortices are not generated at R(r)<3 000 for the forme r and R(r)< 800 for the latter. Although the inner diameters of efflue nt pipes were 2.03, 3.23, and 5.15 cm, effects of the difference were rarely found. However, it was found that the values of R(r) in this li mit were reduced as the viscosity of liquids increased.