An experimental investigation of liquid-solid two-phase pipe flow by simultaneous, two-color digital particle image velocimetry/accelerometry.

摘要

An experimental investigation of two-phase pipe flow was undertaken to study the relationships between fluid and solid phases and turbulent flow characteristics. This was performed by recording simultaneous, two-color, DPIV/DPIA data of a water carrier phase and dilute glass sphere solid phase in vertically upward pipe flow. The analysis consisted of a series of steps to determine, in a systematic manner, insight into the two-phase flow regime. Single-phase DPIV data were obtained first in order to confirm canonical flow parameters and to serve as a baseline for subsequent analyses. A dilute mixture of solid glass spheres was then introduced for study. The simultaneous, two-color DPIV/DPIA measurements provided information on the changing characteristics of mean and fluctuating two-phase flow kinematic and dynamic quantities. The force associated with the solid particle was determined by Newton's Second Law and a force balance Lagrangian equation of motion; results indicated a reasonable correlation between the two equations. The simultaneous, two-color DPIV/DPIA measurements also allowed the calculation and analysis of coupled kinematic and dynamic parameters and statistical correlation terms. It was found that correlation of fluid phase and solid phase velocity was highest in the central region of the pipe. The distribution across the tube of the second central moment of acceleration indicated a higher value for the solid phase than the fluid phase. Both phases had increased values near the wall. The third order central moment skewness statistic of acceleration showed a clear variation between the two phases. The fluid phase acceleration data indicated a sinusoid-type skewness profile across the tube that fluctuated between positive and negative values. The solid phase acceleration data indicated a fairly flat positive skewness profile. These differences were attributed to the inertia of the solid particle and its response to vortical structures. The symmetric profile of the skewness of the fluid phase acceleration distribution provided a means to show the axisymmetric nature of the turbulence.