Simulation Analysis And Experimentalstudy Of Aerator Based On Airfoil Optimization Design Theory

Oxidation ditch treatment technology is widely used in the field of sewage treatment because of its simple process and good water quality.As the most important mechanical equipment of the oxidation ditch process,the aerator determines the treatment efficiency and energy consumption of the oxidation ditch process.The surface aerator used in the domestic oxidation ditch process is mainly low-speed,large-angle inverted cone and wide straight plate.The equipment has the characteristics of low power efficiency,uneven flow rate and high residual sludge.Based on the linear parameters of the blade and the characteristics of the operating parameters,this paper proposes a new aerator blade with a logarithmic spiral as the Streamline and a NACA0012 airfoil as the profile.The highspeed rotating airfoil blade enhances the power efficiency of the aerator and reduces energy consumption by forming a wide range of water jets and sub-circulations on the liquid surface.In order to be able to reveal the aeration mechanism and oxygenation performance of the blade.In this paper,theoretical analysis,numerical simulation and scale-down test method are used to study the oxygen mass transfer efficiency,oxygenation mechanism and motion parameter optimization of the new aerator blades.In this paper,using CFD numerical simulation technology,the variation of fluid in a circular aeration tank under three-dimensional unsteady,gas-liquid two-phase flow VOF model is simulated.The open channel water jet process formed above the free surface,the entrainment lifting effect of the negative pressure region on the back of the blade and the position change of the free liquid surface of the aeration tank were verified.The fluid flow velocity in the aeration tank gradually decreases with the increase of the depth,and the fluid below the liquid surface forms a circulation under the action of the blade lifting force,constantly updating and replenishing the liquid discharged by the jet.The simulation found that the bottom of the blade and the bottom corner of the aeration tank had the lowest velocity and the most likely sludge deposition.Two different angle aerator blades were made using 3D printed fuse deposition technology.The performance test of the aerator blades was carried out using a similar scale with a Froude-like test bench.The effects of different immersion depth,blade rotation speed and blade rotation angle on the oxygenation performance of the aerator were studied.It is found that the standard oxygen total transfer coefficient and standard oxygenation capacity of the aerator are proportional to the blade rotation speed,and the optimal power efficiency point of the blade also appears at high rotation speed.The influence of immersion depth needs to consider the blade rotation speed.The immersion depth has little effect on the aeration performance at low rotation speed.The standard oxygen total transfer coefficient and standard oxygenation capacity of the aerator at high rotation speed increase with the immersion depth.The blades of the two corners are very suitable for aeration and oxygenation at high speed.The range of jet radiation of the 5 degree blade is too large,and the sewage is easily separated from the aeration tank to form secondary pollution,so the rotation speed of the blade is limited.In contrast,a 10 degree blade will perform better at high speeds,and as the speed increases,the power efficiency will continue to increase.