Experimental study of the viscous pump with a helical channel rotor: Torsion effect of the channel

The viscous pump, which has a rotor with a helical square channel, is studied experimentally. The non-dimensional channel curvature is taken to be about 0.1. Three types of torsion of the channel are made to investigate the torsion effect on the flow characteristics. We measure the flux through the channel at a constant rotor speed by changing the pressures at the entrance and exit of the pump. We also observe the secondary flow at a crosssection of the channel. Some of the results obtained are shown as follows: The friction factor along the channel to get the same flux is large for large channel torsion at a constant rotation, and becomes small when the favorable rotation of the rotor to the flow is applied. As for the secondary flow in a cross-section, there appear several types of vortex. When there is no rotation, the secondary flow is almost a symmetric two-vortex type for small flux as is the ordinary Dean vortex, but it changes to a four-vortex type when the flux is large. The secondary flow becomes asymmetric as the rotation is applied. We have unsteady flow patterns at large flux and rotation.