The Chaotic Mixing Mechanism Study Under The Polymer Fluid Flow Field

In this paper, the mixing process of the flow field of the intermeshing mixer and shear mixer are analyzed by computational fluid dynamics and nonlinear theory of knowledge. Respectively, from the Poincare section, the line stretching rate and the average number of lines of tension, Lyapunov exponent angle determines whether there has been chaos in the mixer mixing process.Firstly, briefly describe the research background and the main research content, and summarize the status of the research about the chaotic mixing in recent years.Then, simulating the flow of the intermeshing mixer melt with high viscosity properties is employed in the second chapter through the numerical simulation. The results showed that the rotor speed, the rotor center distance and the mixing of different indoor location have a direct impaction mixing of mixer. Through the Poincare sectional, we can find that increasing the speed of the rotor can promote a "horseshoe" chaos structure to enhance the mixing effect. Decreasing the Rotor center distance can increase the average shear rate and the average shear stress, and enhance the dispersion in the mating area of the melt. Since the rotor and the disturbance action of the fluid is different in different locations, and therefore the release of the fluid away from the rotor position, the resulting dispersion is worse. By averaging the number of lines of tension, Lyapunov exponent, quantitatively proves Poincare section reflected the results.Secondly, in the third chapter focuses on the numerical simulations of the shear mixer. It is analyzed the influence of different cross-sectional shapes of the rotor, different speed and different speed ratio, the initial phase angle on mixer mixing process. The results showed that:Roller rotor mixer for mixing effect is significantly stronger than the Cam rotor mixer. This is because disturbance frequency is higher with three ribs in the Roller rotor than with two ribs in the Cam rotor in the mixing process. Meanwhile, improving the speed can enhance the mixer mixing effect from the disturbance frequency and shear rate. For different speed ratio, the mixing effect of synchronous rotor mixer under the speed ratio1:1condition is stronger than the asynchronous rotor mixer under the speed ratio3:2condition. Because, not only the asymmetry of the speed but also the asymmetric of the rotor structure has impact on melt dispersion.Finally, comparatively analyzing the mixing effect of the two methods leading to chaos in the two-rods mixer in forth chapter, time chaotic mixing and space chaotic mixing. The results prove:the effect of time chaotic mixing is significantly stronger than the effect of the space chaotic mixing. Then, time chaotic mixing method, sinusoidal perturbation, is introduced into the numerical simulation of shear mixer. The results showed that:a sinusoidal perturbation to strengthen the mixer’s mixing efficiency, shorten the mixing time. Ultimately, strengthen the mixing results by chaotic mixing.