Numerical Simulation Technology For Multi-phase Flow And Rotating Flow And Its Applications In Engineering

The rotation of fluid,caused by natural forces or by ingenuity,is a common phenomenon in fluid movement.From tornadoes that run through the world to quantum vortices that are thin as filaments,they all have their own shadows that affect every aspect of our lives.To make the rotating flow available to me,various machines with rotating parts have been invented to assist in some tasks,such as material sorting and mixing.Based on the finite volume method and the multi-phase flow model,this paper makes a comparative study on the simulation effect and applicability of the dynamic mesh method for the flow field of rotating components.Two actual engineering cases are provided for simulation,corresponding mechanism description and treatment solutions are presented from the perspective of fluid mechanics,application range and selection conditions of various calculation models are analyzed,stirring efficiency and optimum conditions of single-axle agitator under different conditions are studied,flow field characteristics formed by magnetic agitator are simulated and analyzed,and combined with conversion rate of chemical reaction.The main results and conclusions are as follows:1)In the multi-phase flow model,Euler model has the largest application range and the corresponding increase of calculation amount compared with other multiphase flow models.The calculation accuracy of the sliding mesh model is much better than that of the multiple reference frames model.The sliding mesh model can reflect the real-time flow field information,but also has a large amount of calculation.2)The numerical simulation of a single-axle mixer shows that the flow field in the stirring tank is mainly rotating flow and the power is generated by the agitation of the paddle blades.The inclined distribution of paddle blades and the coupling effect of wall viscosity cause secondary flow,which enables the material in the tank to exchange axially and achieve stirring effect.The mixing effect of a single-axle mixer can be quantitatively described by the volume fraction of soybean meal powder and the distribution of its relative variance.The optimum speed and initial filling rate of the mixer are 58 rpm and 70%respectively by changing the filling rate of the material and the paddle speed.3)Numerical simulation of magnetic stirrer,rotational flow is the main flow field in the calculation domain,with closed trace rings,closed eddy structures and complex gas-liquid interface evolution,fluid mass exchange in the calculation domain takes on a completely different form from that of a single-axle mixer:gas-liquid interface increases with increasing rotor speed;The intensity of secondary flow increases first and then decreases with increasing rotor speed;Increased liquid surface area increases the incident surface of ultraviolet radiation;Secondary flow rate and gas-liquid interface area are highly correlated with the conversion rate of cinnamaldehyde.In this paper,multiphase rotating flow technology is applied in engineering and its application range is extended.