ABSTRACT
ABSTRACT: The sedimentation of flocs or solid particles has to be taken into account when a coaxial cylinder rheometer is used to deal with the flocculated suspensions or pulps. An important approach to the problem is to make the test fluid circulate from the bottom to the top of the rheometer through an external channel. In order to examine the influence of fluid circulation on the rheometer operation, a careful hydro mechanical analysis about the shear stress on the piddle surface is done in the paper, and some important results founded. The investigation proves that if the circulated fluid does not introduce any additional velocities in the tangential and radial directions within the operation space of the rheometer, the basic principles of the rheometer will not be changed although an axial movement is attached to the fluid because of the circulation. In addition, the circulated fluid needs to be evenly distributed on the whole cross-section of the operation space, otherwise the correction of the measurements is necessary.
