Central Tornado Flow Stirring Tank Internal Single-phase Flow Field Numerical Simulation Research

The structure of the Center Tornado Flow Stirred Tank is simple. It is evenly distributed four logarithmic spiral deflector at the bottom of the tank, blade is installed in the vicinity of the liquid level of the internal tank, mixing shaft is short, energy-efficient is good, cost is low. When the blade is rotating high-speedily, it forms upward spiral flow liking a tornado in the center of the tank, mixing effects of the fluid is good, and the operation is stable.In this paper, the internal flow field characteristics in the stirred tanks are simulated qualitatively based on CFD, including the influence of different blade forms, different diameter of stirred tank, different angle of logarithmic spiral deflector, different angle of polar angle, different initial radius, different height of deflector, different thickness of deflector, different height of blade, different diameter of blade, different width of blade to the mixing flow field in the tank in order to achieve the purpose of optimal design. It is founded that the geometric dimensions of stirred tank, deflector, and blade have a significant effect on its macroscopic flow field, and when the diameter of tank is300mm. six straight disc blade, the angle of logarithmic spiral deflector is45°, the polar angle is60°.the initial radius is20mm, the height of deflector is30mm, the thickness of deflector is5mm, the height of blade is5T/6, the diameter of blade is T/2,the width of blade is T/10, it forms two circular flow, the tornado flow effect is obvious, the hybrid effect is better.Based on the optimization design results, the influence of rotation speed, liquid viscosity and non-steady-state analysis method to the flow field characteristics have been investigated. Results indicated that with the increase of stir speed, torque and the power consumption are gradually increasing. The viscosity of sucrose solution is increasing with concentration’s increase.When its viscosity is relatively high, Turbulent eddy current number reduce, mechanical energy of the fluid convert into its heat, the mixing effect of fluid at the bottom is not good. In the steady-state analysis, the speed of the rotating domain is homogenized. In the non-steady-state analysis, the shape and position of circular flow in macroscopic flow field is the same with the steady-state,and taking into account the instantaneous state of the flow field,so the peak speed of the entire flow field is bigger than the average speed in the steady state, the computation time is longer, the accuracy of the flow field is higher.and it reflect better actual situation of the movement of the flow field.