Unsteady flow in rotating drums using laser Doppler velocimetry

Abstract

Non-destructive measurements by laser Doppler velocimetry is employed to study unsteady flow in a hollow drum filled with liquid. The drum is suddenly accelerated from rest or is suddenly decelerated from a steady rotation to rest. Pure water and glycerin-water mixtures are used as the test liquid in which polyethylenelatex particles are mixed as the light scattering tracer. The boundary layer formation, the time history of velocity, momentum and kinetic energy of the liquid, the wall-to-fluid force transfer, and the transient response time are determined. Also determined are the effects of side walls and fluid viscosity on the transient flow response. Of importance is the disclosure of Ekman layer instability near the inner radial wall of the test drum. It is actuated by the centripetal acceleration-induced buoyancy force.

Thermal Fluid Flow Transport Phenomenon in Unsteady Rotating Drumduring Spin‐Down Process

“…The boundary conditions in the axially rotating drum are specified as follows: To discretize the governing equations, the finite difference method is employed here. Note that this method is based on the conservative formulation, although the governing equations (1), (2), and (3) are written in nonconservative form. The system variables P, U, V , W, and T are calculated with a staggered grid.…”

“…Unsteady transport phenomena in hollow drum subjected to a sudden acceleration and deceleration were experimentally studied by means of laser doppler velocimetry (Kawashima and Yang [2]). The corresponding theoretical study was performed by Yang and Kawashima [3].…”

The Origin of Ekman Flow in a Cavity Subject to Impulsive Rotational Motions

“…These studies include measurements of velocity by means of LDV (Kawashima and Yang, 1988), hydrodynamic theory (Yang and Kawashima, 1990a), unsteady recirculating flow with inner surface heating measured by flow visualization using the tracer/light sheet method (Kawashima and Yang, 1990a), flow patterns measured by means of double-exposure photography combined with temperature measurement by means of thermocouples Yang, 1990b, 1992a;Yang and Kawashima, 1990b (Kawashima et al, 1992b, c), formation of Ekman boundary layers (Ohue et al, 1995), temperature distribution inside a rotating drum with inner surface heating or cooling (Ohue et al, 1996a(Ohue et al, , b, 1998 and imposition of three distinct thermal conditions; adiabatic, heating and cooling, on the inner cylinder surface (Kawashima et al, 1999). This study represents a further continuation of this series.…”