A study of the flow of particulate suspensions using a laser doppler velocimeter

A study of the motion of droplets and particles suspended in a turbulent air flow was performed. A Laser Doppler Velocimeter (LDV) was designed and constructed for use in measuring two components of velocity for individual droplets or particles. The LDV could be used at any radial position in the pipe. As a check on the accuracy and reliability of the LDV method, LDV measurements were compared with hot wire anemometer measurements for the same flow conditions. For these verification experiments the seeding particles required by the LDV were chosen to be small enough that they precisely followed the air flow. In general, the agreement between the two types of measurements was very good. The LDV was also used, to measure the velocities of 20 ym dioctyl-phthalate droplets and 63 urn glass beads. A variety of statistics were generated. Theoretical predictions were made of the axial mean velocities, the axial root mean square velocities, and the radial root mean square velocities for the entrained particles. Fairly good agreement was observed between theory and data.