PHASE DISTRIBUTION AND TURBULENCE STRUCTURE FOR SOLID FLUID UPFLOW INA PIPE

The phase distribution and turbulence structure for solid/fluid upflow in a vertical pipe were investigated. Spherical particles, approximat ely 2 mm in diameter, were used and runs were made with particles havi ng two different specific gravities. In particular, ceramic particles, which were heavier than water, and expanded polystyrene particles, wh ich were lighter than water, were used. A new method is presented for the measurement of the volume fraction in solid/fluid two-phase flows using a laser-Doppler anemometer (LDA). The measured local time fracti ons obtained with the LDA must be corrected, because bias is produced by the presence of natural seeding, the finite size of the measurement volume and interruptions of the laser beams by the dispersed particle s. An analytical method has been developed which accounts for these ef fects. A single-beam traversing gamma-ray densitometer was used as a r eference against which to assess the volume fraction correction method . Good agreement between the corrected LDA and gamma-ray densitometer results was obtained. The volume fraction profiles show that at low fl ow rates the ceramic particles have an almost uniform distribution, wh ile increasing the flow rate causes coring. In contrast, the phase dis tribution of the light polystyrene particles had wall peaking for both the low and high flow rates. However, wall peaking was flattened as l iquid flow rate was increased.