Influence Of Guide Vane Geometry On The Performance Of Large Vertical Centrifugal Pump

Large vertical worm gear centrifugal pump has the advantages of high flow,high head and high power,which has a broad application prospect and urgent market demand in water conservancy engineering construction and agricultural irrigation.This paper takes large vertical centrifugal pump as the research object,based on the SST k-ω turbulence model and Zwart cavitation model using ANSYS software,proposes to change the guide vane inlet and outlet placement angle and the style of spacer for a total of six options,and conducts numerical simulation calculations on the whole flow channel of vertical centrifugal pump,analyzes and compares the flow field,cavitation performance and hydraulic stability of the centrifugal pump under each option,and explores the influence of each option on the centrifugal pump.The research results have some reference value for the selection of guide vane placement angle and spacer style of centrifugal pump.The main research contents are as follows:(1)Through numerical simulation of centrifugal pumps with different guide vane inlet and outlet angles,the impact of changing the guide vane inlet and outlet angles on centrifugal pumps is analysed.The reshaping of the special guide vane can effectively reduce the impact of the fluid flowing from the guide vane into the worm shell.By modifying the position of the spacer and changing the angle of placement of the guide vane,the internal flow characteristics of the centrifugal pump at low flow rates have been greatly improved.(2)Numerical calculations of the cavitation performance of the centrifugal pump were carried out for the inlet and outlet and spacer schemes,which showed that the cavitation pattern was similar for all schemes,with the head starting to fall at NPSHa = 1.745 m.The rate of fall differed between the schemes,with the spacer and outlet schemes falling faster and the cavitation performance worse than the inlet scheme.The septum scheme has the fastest cavitation development,the largest bubble area on the rotor blades and more uneven blade loading.(3)In the design condition,the effect of changing the angle of inlet and outlet placement of the guide vane and the style of the spacer on the pressure pulsation pattern characteristics of the centrifugal pump and the radial force at the impeller was studied by unsteady calculations,and the results showed that: the pressure coefficient of the modified scheme was significantly reduced compared to the prototype pump,and the monitoring points in the rotor position arrangement,the inlet scheme reduced the peak-to-valley difference compared to the prototype pump,and the pressure fluctuation was no longer violent.The amplitude of the monitoring points in the special guide vane arrangement exceeds that of the next flow path.The number of peaks and troughs at each monitoring point during the cycle corresponds to the number of guide vanes.The appropriate reduction of the guide vane inlet angle reduces the amplitude of pressure pulsations to a certain extent,which is conducive to the stable operation of the unit.