PIV Experimental Research And Analysis On The Velocity Field Of Converging Channel In A Rheometer For Measuring Generalized Viscosity

Studies of shear viscosity and flow for rheology and mechanics have been done.Measurement of the shear viscosity has development for many years. The technic is mature.However, shear flow and extensional flow are synchronously existent in actual flow. In view of this, a generalized viscosity model and experimental device have been proposed for generalized Newtonian fluids.With this generalized viscosity model, shear viscosity and extensional viscosity can be measured simultaneously.The velocity field of converging channel in a rheometer for measuring generalized viscosity of polymer melts is very important for testify the rationality of a generalized viscosity model. Particle Image Velocimetry provides effective means for measuring and research the velocity field of converging channel.In order to research on the velocity field of converging channel in a rheometer for measuring generalized viscosity of polymer melts, an experimental project and organic glass of converging flow in the rheometer was established. Particle images of Newtonian-fluid polybutadiene and Non-Newtonian-fluid CMC in the flow field of converging channel in the rheometer were shot by PIV system. The velocity field of converging channel in the rheometer can be obtained through analysis of image and data with Tecplot and Origin softwares. The analysis results show that the PIV experimental results of Newtonian-fluid polybutadiene are in accordance with the POLYFLOW simulation and the theoretical calculation data. It proves that the way to obtain the velocity field of converging channel for Newtonian-fluid polybutadiene and Non-Newtonian-fluid CMC from the PIV experiment is feasible.When four rheological parametersσ,τ,ε,γare obtained by measurement and calculation of flow rate and pressure drop of converging channel for Newtonian-fluid polybutadiene and Non- Newtonian-fluid CMC, pure shear viscosity at channel wall and pure extensional viscosity at core axis of Newtonian-fluid polybutadiene and Non- Newtonian-fluid CMC are calculated by the generalized viscosity model. They characterize different performances of Newtonian-fluid polybutadiene and Non- Newtonian-fluid CMC, respectively.It testifies the rationality of a generalized viscosity model of polymer melts.