Numerical Simulations On The Periphery Flow Field Of Water-lifting Aerator And The Flow Field Of Aeration Chamber

The Ware-lifting Aerator, aiming at the water quality problems of eutrophication and pollutants' releasing from sediments in deep water source reservoir, is a new water quality improvement device, which can mix water and oxygenate water. Through the way of mixing water, Ware-lifting Aerator can send alga to the lower lay of the water and make it to death by restraining alga's growth. Also it can improvement the anaerobic state in lower water by mixing water or oxygenating water directly. So the pollutants' releasing from sediment in water source is controlled.Computational Fluid Dynamics, short for CFD, is the analysis on the system which contains the relative physical parameters of fluid dynamics and heat conduction. CFD can be considered a kind of numerical simulations base on flow basic equations (mass conservation equation, momentum conservation equation, energy conservation equation). Through this kind of numerical simulations, we can get the distribution of fundamental physical parameters (such as velocity, temperature, pressure, concentration) in any places of a very complicated flow field and the changing process of these parameters as the time changing. FLUENT is one of the CFD software, which is the most comprehensive, most widely applicability and most widely used CFD software. The practice has proof that FLUENT has powerful computing capabilities and can be used to solve the problems of air and water' motion and heat conduction.Through the Numerical simulations on the periphery flow field of Water-lifting Aerator and the flow field of Aeration room this article can get these conclusions:(1) The direction of rotation will change because the included angle between hydro-deflector and horizontal plane changes. Through numerical simulations, we know that 37°is the key point at which the direction of rotation inverses. As the included angle changing from 0°to 37°, the direction of rotation also inversing, the alga-removed area will increase by 20%. If we increase the included angle further, bigger than 37°, the alga-removed area will not increase any more.If the inlet velocity condition and the direction of rotation are the same, the changing of the included angle can not affect the mixed strength of the flow field.(2) If the radiuses of water are the same, increasing the inlet velocity can not expend the alga-removed area, but it can make it faster to form a steady flow field, and at the same time, strengthen the mixed strength.If the inlet velocity are the same, increasing the radius of water from 50m to 100m, the alga-removed area will be reduced, following the mixed strength being weakened and the time which forming a steady flow field needs increasing greatly.(3) The quantity of lifted water increases as the radius of the air bubble increasing. If the radius of the air bubble increases from 1mm to 5mm, the quantity of lifted water increases by 253.69%. And form 5mm to 10mm, the quantity of lifted water increases by 13.94%.(4) When the radius of air bubble is smaller than 5mm, there are more than 50% bubbles go into the back-flow room following the water flow, and then being sent into bottom water. And also because the air bubbles which have smaller radius get more effective interaction with water, the smaller air bubbles can oxygenate water better. Small air bubbles are not good for the separation between air and water. So more time will be needed to form an air-bullet.