Research And Numerical Analysis On Pressure Pulse Of Low-consistency Centrifugal Pulp Pump

With the advantages of simple structure, stable operation and high efficiency, centrifugal pumps have being widely used in metallurgy, paper making, irrigation and drainage, etc... In the industry of paper making, with the gradually high demand of quality and output of paper, low-pulse centrifugal pumps are very popular in the technological process, which can reduce the pressure pulse of outlet considerably.This paper has mainly analyzed the pressure pulse of centrifugal pump theoretically and brings forward optimized projects. Numerical simulation forecasts the feasibility of improvement, and also supports the further development of low-pulse pump. The main work and results are outlined as following:1. By analyzing the flow status producing in and out of impeller and studying the mechanism of pressure pulse in centrifugal pulp pump, we can get the main affect factors of pressure pulse, such as cavitations, back flow, eddy flow, shape of impeller, vane and casing tongues, etc..2. Main approaches to reduce the pressure pulse are analyzed. From the hydraulic design for parts of water passing, we offered several optimized projects for this pump, such as optimizing the array of vane, changing the size of base circle, shape of impeller and vane, type of tongue, etc... Analyze the feasibility of projects theoretically and confirm its meanings to reduce pressure fluctuation.3. The model of 3-D flow in centrifugal pump is established. Because of the complexity of computational areas, we choose Pro-Engineer as a modeling tool, and then import the STP file to Gambit to partition grid. Considering the different flow status in impeller and casing, we divide the model into two zones and have acquired satisfactory grid quality and quicker convergence speed.4. By means of the CFD tools—Fluent, which use Finite Volume Method to solve the general N-S equation, several flow parameters are acquired. The simulation of this paper is computed under the assumption of steady flow, and then transit to unsteady flow, at last we can get all the parameters in different times and different impeller positions. This way can not only guarantee the precision, but also the speed of computation.5. By using the treatment function of FLUENT, we can catch the pressure of outlet, and then handle the digital information by ORIGIN; at last we can get 2-D graphs of pressure pulse.6. After analyzing the results of all optimized schemes, we can conclude that the stagger arranges of vane, increased diameter of base circle, ladder tongue of casing, more blades of impeller are all good ways to reduce the outlet pressure pulse of centrifugal pump.7. Referring to pump with stagger impeller and comparing the results of simulation with experiment data's, we can get a relative good result. The result of comparison in some sense validates the precision of simulation of Fluent.