The 3-D flow field relative to a rotating Rushton turbine blade is acq
uired for fully turbulent tank conditions by synchronizing LDA measure
ments with the output of a shaft-mounted encoder. This makes it possib
le to capture the impeller stream velocity field, including the detail
s of the vortices behind the blades. Mean velocity data at three impel
ler speeds show the extent of periodicity and the axes and structure o
f the vortices. Pumping capacities are determined and it is shown that
the radial jet is a consequence of fluid entrainment into the vortice
s. Deformation rates based on gradients of mean velocity are calculate
d. Close to the blade they can exceed impeller rotational frequency by
as much as two orders of magnitude. To a first approximation, the nor
malized mean flow field is independent of impeller speed.