Pr. Bandyopadhyay et M. Gadelhak, ROTATING GAS-LIQUID FLOWS IN FINITE CYLINDERS - SENSITIVITY OF STANDING VORTICES TO END EFFECTS, Experiments in fluids, 21(2), 1996, pp. 124-138
The spiraling and straight gas-filled vortices formed by a rotating mi
xture of a gas and a liquid flowing through a finite-length cylinder a
re the subject of this paper. The working fluids considered are primar
ily helium and water. The bubbly liquid enters and leaves the cyclone-
type separator tangentially. A gas-core vortex forms due to the result
ing swirling motion of the mixture and, ideally, most of the gas leave
s through an opening centered in the inlet end-wall of the vertical cy
linder. The sensitivity of the gas-core configurations to the relative
angle between the tangential inlet and outlet (phi) and to the length
-to-diameter ratio of the cylinder (L/D) are investigated experimental
ly. Direct observations of the flow field are made using video and sti
ll cameras. The various gas-core vortex configurations are classified
in a stability diagram. Although, as many as eight different types of
core patterns have been identified, they are of two basic modes: strai
ght and helical-spiral, or combinations of these. However, the straigh
t mode is neither perfectly straight nor axisymmetric; it contains som
e non-uniformities. In an L/D-versus-phi plane, a linear ridge exists
that is a sensitive stability line dividing the regimes of the straigh
t and helical-spiral modes. The relationship between the two modes is
examined, and the statistics of the wavelength and diameter of the hel
ical spiral are given. A kinematic model is deducted and is used to ex
plain the observed changes in the geometric parameters of the gas core
.