4WS, 4WH and 6WI rotors were regarded as the object of study. According to the theory of fluidstructure interaction, fluid solid coupled finite element analysis models of internal mixer were established, and the coupled equations of liquid material and solid rotor inside internal mixer were solved. Under the circumstance of constant power, the influence rules of the stress and deformation of rotor under rotate speed were researched. It was found that the stress and deformation were leaded by the coupling of torque and fluid load , and the torque was the main factor resulting in stress and deformation. With the increase of rotate speed, the mixing effect of materials was significantly improved. The torque caused by rotate speed and the change of fluid load leaded to the change of rotor clearance. Rotor clearance had significant influence on the mixing effect. 6WI rotor had better mixing effect. The research results provided theoretical reference for the reasonable design and performance prediction of rotor in internal mixer.

Based on the computational fluid dynamics theory, the physical mixing modeling of highdensity polyethylene (HDPE) and polystyrene (PS) in a internal batch mixer was established. By using Fluent software, the process of the mixed polymer in the mixer with double rotor was studied. The results showed thatthe mixing efficiency and asymmetry of the flow field were improved when the twinrotor mixer rotated in higher speed. After a period of time, the single polymer volume fraction at each position reached steady in the extruder.

Three dimensional mixing characteristics of the kneading elements in a intermeshing corotating triscrew extruders were simulated. The mesh superposition technique (MST) and the CarreauBird flow model were employed in this simulation. The mixing mechanisms in the kneading elements were analyzed with the mixing evaluation parameters, such as maximal shear rate, mixing index, instantaneous and time averaged efficiencies, which were compared with those in the twin screw extruders. The results show that, in the same operating conditions, the maximal shear rate, mixing index, instantaneous and time averaged efficiencies of the triscrew extruders are bigger than those of the twin screw extruder. It shows that the triscrew extruder has better mixing efficiency than the twin screw extruder.

When the vibration of heat exchanger tube bundle is large induced by fluid, the collisions between the tube and baffle will take place at the maximum amplitude of the tube, which leads to tube fretting wear and damage. The transient finite element analysis of fluidinduced vibration response for a heat exchanger tube was employed with ANSYS software. On this basis, the phenomenon of random rubbing between the bezel and tube was studied due to the larger vibration amplitudes of the tube. The nonlinear dynamic response and vibration rules of the random collisions between the bezel and tube were calculated. The calculated results provide a theory of reference for the design of heat exchanger tube bundles.

Drilling is a complex transient process. Speed will reduce instantly when drillstring hits a hard rock suddenly and an accelerate process follows it until the speed accelerates to normal value. To observe the dynamic characteristics of drillstring in this case, using the finite element software "ANSYS" to analyze a constant speed process and accelerate processes of drillstring system in vertical well and gets the discipline of drillstring's vibration. The results show that after hitting hard rocks, the collision between drillstring and the borehole wall will happen for the hitting effect between rocks and bit, and the collision strength has a great relationship with acceleration time, if the acceleration time is short, the collision is slight and the force is small; if the acceleration time is long, the vibration will be exacerbated significantly, the collision is more serious and the force increases. In a word, the variable speed of drillstring exacerbates its vibration.