The Research Of The Mixing Ability In Extensional Flow Static Mixer

Extension flow is an important flow pattern in polymer mixing process which plays an important role in dispersion and distribution mixing. Extension Flow Static Mixer (short for SEFM) generates extension flow and is a very important equiment in polymer mixing process.In this study, professional CFD (Computational Fluid Dynamics) software, POLYFLOW, was adopted. By this software, the contribution to mixing performance of every SEFM plate structure’s parameters was simulated. Pressure distribution curve, stretching-rate distribution curve, shearing-rate distribution curve and residence time distribution curve for every parameter condition were calculated. On the basis of this, the contribution SEFM mixing performance of every plate structure and parameter was compared. The fact told us that the pressure loss was least when the plate structure was curve geometry for both sides. Under this condition, the width of residence time distribution was the widest and cumulative residence time was the longest. Also, the average stretching-rate and the maximum cumulative stretching-rate were lager. It was also found that more plate edges had a positive effect on performance. The height of plate edge played an important role on stretching-rate and residence time distribution. The chamfer of plate topmost edge is a main factor on shearing rate. The changed of the pressure loss is main lie on the angle of plate edge. The diameter of exit only had influence on the whole pressure loss.The mixing performance of typical structures SEFM was analyzed by experiments. The contribution to mixing performance of different plate edge gap was also researched. It can be concluded from the experiments that whether there was plate structure or not had an important influence on mixing performance. Different plate structure had different mixing performance for SEFM. The mixing performance varied largely with the gap between plate edges under the same plate structure condition. As the gap between plate edges increased, the average particle size of the blend dispersed phase gradually increased first and then decreased for a while, after that increased gradually again. That is to say, as the gap between plate edges increased, the mixing performance became worse first and better for a while and after that worse again. It needed to choose a suitable gap for plate edge in order to acquire better mixing performance in the application of Extension Flow Static Mixer.