Analysis Of Backflow Vortex And Cavitation Of High Speed Centrifugal Pump

High speed centrifugal pump is a kind of special centrifugal pump with small flow and high head.Due to the high speed,it is very easy to produce the backflow vortex and cavitation.There are many methods to reduce the backflow vortex and cavitation.In this way,the method of adding the orifice plate before the impeller can effectively suppress the cavitation and backflow vortex,which can improve the hydraulic performance of the high speed pump.But there is no scholar to change the shape of the orifice plate to test its impact on the backflow vortex.In this paper,through the modification design of the orifice plate,the influence of the backflow vortex and cavitation of the high speed pump is analyzed,and a set of optimal orifice plate form is selected.First of all,through the analysis of single phase constant to determine the size of the orifice plate,orthogonal experimental method is used to determine the best the orifice plate thickness,distance the orifice plate and from the inducer import and the diameter.Design a total of nine kinds of schemes.Secondly,the change before and after angle the orifice plate,designed a total of 25 kinds of schemes,then for further analysis and comparison.Finally,five kinds of scheme for the calculation of cavitation erosion condition,and then make a comprehensive performance comparison,selected the backflow vortex inhibition effect is good,the most obvious solution to improve high-speed pump cavitation erosion.The conclusions are as follows:(1)In this paper,the basic size of the orifice plate adapted to this high-speed centrifugal pump is obtained by orthogonal test,the thickness of the orifice plate B=20mm,the distance of the orifice plate from the inducer inlet L=1.15 R,the diameter of the orifice plate D0=1.5R,R for the inlet section of the radius.(2)In this paper,under the design conditions,both-10°/20° and-20°/10°on the control of the backflow vortex,the internal flow field and cavitation of the inducer and impeller,Relative to other programs have a great advantage.In the small flow conditions,the-20°/10°scheme has good effect on the inlet backflow vortex.The pressure of the suction and pressure surfaces of impeller changed little,and the best result of cavitation is-20°/10° and 20°/20°.(3)The external characteristic of high speed pump was analyzed,and the observation of head curve,under small flow rate 0.6Qd conditions,the largest increase in head scheme is20°/20°.Under the design condition,the largest increase in head is-20°/10° and-10°/20°.To observe the efficiency curve in 0.6Qd low flow conditions,improve the efficiency of the maximum solution for 0°/0°;in the design condition,the efficiency reached a maximum value,to improve the efficiency of the maximum-20°/10° and-10°/20° scheme,the efficiency of the two schemes is greater than the traditional orifice plate 0°/0° in about 2 percentage points.In summary,this paper proposes a kind of orifice plate device which suppresses the cavitation of the high speed pump,which can effectively suppress the backflow vortex of the pump and the cavitation of the pump,and effectively improve the hydraulic performance of the high speed pump.