Numerical Study On Performance Of Water Ring Vacuum Pumps

Water ring vacuum pump is widely used in petrochemical,coal industry and papermaking industry.However,the problem of low efficiency and high energy consumption still exists.With the development trend of large scale water ring vacuum pump,the demand for energy saving and consumption reduction of water ring vacuum pump is more and more urgent.The study on working process of water ring vacuum pump has been not enough,due to it's complex flow and special working principle.A simplified model of water ring vacuum pump was established to study the shape of water ring boundary.An ideal shape of water ring boundary was got and the reason of water ring boundary was explained with pressure and velocity distribution of water ring vacuum pump.And a performance estimation method was proposed with the help of theoretical derivation.A normal working model of water ring vacuum pump was established to simulate the twophase flow in water ring vacuum pump.The pressure,velocity and two-phase distribution of water ring vacuum pump were obtained.The forming process of water ring vacuum pump was analyzed.A stable water ring which is tangent with the hub will form when water is adequate.Gas and liquid are not likely to mix in inlet area,but gas-liquid mixing is very obvious in outlet area.Finally,the flow rate of supply water was obtained.By changing the working parameters of the water ring vacuum pump,the influence of the speed,the viscosity of the liquid,the type of the blade and t he amount of water on the shaft power and inspiration capacity of the water ring vacuum pump were explored.It indicates that the type of the blade has little influence on the inspiration capacity of the water ring vacuum pump.But straight blade model can cause higher pressure,more vortex and more serious gasliquid mixing extent.Water ring vacuum pump with arc blade has lower energy consumption and improved arc blade should be used in water ring vacuum pump.Appropriate increase in the size of the pump casing of the suction section of the water ring vacuum pump will help to enhance the suction capacity of the water ring vacuum pump.The gas at the outlet side of the axial clearance can flow along the hub to the suction port side under the pressure,which will decrease the suction capacity and the vacuum degree of water ring vacuum pump.Study also found that with the increase of rotating speed,inspiratory capacity and shaft power has gradually improved,isothermal compression efficiency decreased gradually.Effects of viscosity of working fluid on the inspiratory capacity is not obvious,but the viscosity can easily increase shaft power.Viscosity of working fluid should not be more than 0.1 Pa·s.Working water amount has great influence to suction capacity and shaft power of water ring vacuum pump.Water ring tangent with the hub can't form when working water is not enough,and the clearance between the water ring boundary and the hub will decrease the suction capacity and vacuum degree of water ring vacuum pump.The amount of working water should be adjusted according to the inlet pressure.The study is of guiding significance to the structure design,model selection and working operation of water ring vacuum pump.