PIV measurement and study on turbulence generator flow field of medium consistency pump

Abstract

In order to study the flow characteristic in turbulence generator of medium consistency pump, a particle image velocimetry (PIV) test rig was established. 2D-plane flow field was acquired fast and effective by adjusting the angle and position of mirror. For investigating the effect of speed on flow field, velocity and turbulent kinetic energy were measured at speed 80r/min, 130r/min and 200r/min. Dimensionless method was adopted to analyze flow field by quantitative approach. The results showed that on vertical flow plane axial velocities decreased with radius increasing in the region of turbulence generator blade, and axial velocity direction was changed and increased with radius increasing outside the region of turbulence generator blade. Internal flow direction of turbulence generator was at opposite direction with outside flow. Fluid flows from inlet to outlet of turbulence generator blade and then go back to inlet, which forms a circle. On horizontal flow plane, circumferential velocity increase with radius increasing firstly, and then the maximum appears at outer diameter of turbulence generator, and last it decreases gradually. Turbulent kinetic energy increases with rotational speed increasing at inner of turbulence generator flow field, and high turbulent kinetic energy mainly concentrates near the blade inlet and external diameter of turbulence generator. Therefore, in order to achieve better turbulence effect, high turbulent kinetic energy can be obtained by changing the shape of blade inlet structure, increasing the blade outside diameter and improving rotational speed.