The vortex depth in an agitated vessel with paddle impeller is measured und
er various impeller dimensions and various baffle conditions. The vortex de
pth in a nan-baffled vessel is correlated well by using the Froude number a
nd the parameter n(p)(0.7)(b/H) which is defined for the power correlation
by Kamei et al. The difference of the vortex depth in a baffled vessel from
that in a non-baffled vessel is also correlated by using the baffle condit
ion parameter n(b)(0.8)(B-w/D). The radius at the intersection of liquid fr
ee surface and static level is only affected by the ratio of the paddle imp
eller diameter to the vessel diameter. A new estimation method of the radiu
s of cylindrically rotating zone from the vortex depth and the intersection
radius was proposed. The radius of cylindrically rotating zone decreases w
ith increasing baffle condition parameter (h(B)/H) n(b)(0.8)(B-w/D) and van
ishes where the baffled condition parameter is 0.24. This condition is inde
pendent of the impeller dimensions, and is weaker than the full baffle cond
ition.