Numerical simulation of three blade diving mixer
Submersible mixer is an indispensable mixing machine in sewage treatment process. It absorbs the power of main engine by rotating motion and generates induction speed, then generates thrust force and movement to the fluid, keeps the mixed liquid in sewage treatment mixing tank at a certain flow rate, prevents activated sludge from depositing at the bottom of the tank, and returns the sewage to the tank. The mixing of flow and recirculating flow makes the suspended solids evenly distributed, so that there is sufficient contact between microorganisms and sewage to realize mixing stirring and propulsion. Generally, the flow velocity of water in the pond is about 0.3 m/s, so as to ensure that the reaction of sewage in the pond can be fully carried out.
Hydraulic performance of submersible mixer can be judged by effective axial propulsion distance and effective disturbance radius of water cross section. At present, there are few reports on submersible mixer at home and abroad. In this paper, three-dimensional numerical simulation of flow field in sewage treatment tank of submersible mixer is carried out by using computational fluid dynamics software Fluent 6.3. Through the analysis of the velocity field at different sections of the tank, the characteristics and rules of the internal flow field in this kind of sewage treatment stirring tank are obtained. At the same time, the hydraulic characteristics and power characteristics of the submersible mixer are studied to select the appropriate motor.
According to the design drawings of the submersible mixer, the submersible mixer is designed by Pro/E three-dimensional modeling software. The surface is generated by scanning and mixing, then the surface is connected and smoothed to complete the overall modeling of the blade, as shown in Figure 1. The submersible mixer blade adopts airfoil blade, and the number of blades is the same. 3. The diameter of the blade is 400 m M. The size of the pool is 7.0 m x 3.0 m x 2.4 M. The medium is water under normal temperature and pressure. The speed of the diving mixer is 740 r/min. It is installed in the middle of the side wall of the pool 1.0 m away from the bottom of the pool. The power of the motor is 4.0, 3.0, 2.5 and 1.5 kW, respectively.
At present, there are few reports on the research of submersible mixer at home and abroad. In this paper, the three-dimensional numerical simulation of the flow field in the sewage treatment tank of submersible mixer is carried out by using computational fluid dynamics software Fluent 6.3. The velocity field at different sections of the tank is analyzed to obtain the internal flow of such sewage treatment mixing tank. At the same time, the hydraulic characteristics and power characteristics of the submersible mixer are studied to select the appropriate motor.