Measurement of turbulent flow fields in a stirred vessel with four bafflesby Laser-Doppler velocimetry (Analysis with periodic averaged velocity profiles)

The 3-D flow field relative to a rotating paddle blade is obtained by synch ronizing LDV measurements with the output of a shaft-mounted encoder, thus making it possible to determine the impeller stream velocity field, includi ng details of the discharge flow region behind the blades. Mean velocities, ensemble-averaged between a specific impeller blade pair (over 90 degrees) show the extent determined from both the passage and structure of the disc harge Aom region. Pumping capacities are consequence of fluid entrainment i nto the discharge flow region. Mean velocities taken in a rotating frame of reference reveal a significant periodic variation near to those taken in a fixed frame.