Measurement and Analysis of Turbulent Flow of Wood Pulp Fiber Suspensions

Abstract

In a previous report techniques were described for measuring turbulence and velocity profiles in turbulent shear flows of water and dilute fiber suspensions, and some preliminary results presented. The present report describes subsequent experience with the techniques, and the results of their application to an extended range of flow velocities and an additional wood pulp suspension. The report has two areas of emphasis. The first has to do with some basic facts about turbulence, together with relevant theoretical relations among variables and their implications as regards problems of measurement and analysis. The second relates to the specific -measurements and their significance as regards flowing fiber suspensions. The results confirm and extend the previous conclusions regarding the .mechanism of turbulence and the momentum transfer process in dilute fiber suspensions. In particular, the significance of the combined roles of turbulence and fiber entanglement in diffusion and mixing is examined in detail. The necessity of isolating these roles is discussed and recommendations presented. The procedures employed for data measurement and analysis of the statistically turbulent flow are: analyzed and recommendations made.