Research On Pulsation Characteristic Of Internal Flow Field In A Centrifugal Pump Affected By Volute

As a general-purpose machinery,centrifugal pump plays an extremely important role in the national economy.In the operation of the centrifugal pump,because of the phenomenon of fluid separation,cavitation,hydraulic vibration and so on,make its internal flow field show three-dimensional unsteady turbulent flow,also with strong vibration and noise,which will seriously affect the operation of the system and equipment safety and service life.With the rapid development of economy,the important national policys,environmental protection,energy saving and consumption reduction are advocated,therefore,indicators of vibration and noise of pump products become problems needed further study.The methods of changing tongue type and the clearance between tongue and impeller,have become a hot problem in the study on centrifugal pump pulse characteristics.By analyzing the mechanism of centrifugal pump vibration noise induced,inspired by centrifugal fan noise reduction technology,based on the principle of bionics,long-eared owl surface noise characteristics regarded as biological prototypes,and connecting with the hydraulic design method of centrifugal pump,centrifugal pump double volute tongue,bionic volute model are builded.Through the method of combining theoretical analysis,numerical simulation and experiment,the noise reduction performance of double volute tongue insulation and bionic volute is researched,and analyzing theoretically the mechanism of damping noise reduction.The main work and creative achievements,as follows:1.Double volute tongue structure model is established,which based on the traditional centrifugal pump hydraulic design method to determine the structure size and orientation of two tongues,in ensuring that the structure of double volute tongue does not affect the external characteristic performance or influence is extremely weak,the sliding mesh technology is used to comparative study pressure fluctuation characteristics,radial force ripple characteristics on each section in pressurized water chamber,and the characteristics on the internal flow field of single and double volute tongue under different working conditions.Results show: pressure pulsation amplitude on cross sections in pressurized water chamber,radial force ripple amplitude in volute and impeller all decrease significantly when the double-tongue applied under different working conditions.And the flow state in internal flow field is better and velocity gradient is more evenly especially near the tongue,which is more conducive to flow.2.The macroscopic bionic volute model with Long-eared owl wings characteristics is established,the structure size and location of bionic volute based on centrifugal fan bionic noise reduction technology,the traditional centrifugal pump hydraulic design method and pulse characteristics of the research status,in ensuring that bionic structure of the spiral case does not affect the external characteristic performance or influence is extremely weak.Under different working conditions,pulsation characteristics at the top of different tongues are analyzed,differences of static pressure field and velocity field on the internal flow field of different volutes on different time are studied,pressure pulsation characteristics in pressurized water chamber of different volutes are analyzed.Results show: pressure pulsation amplitude locate at D5 in tongue area,which could drop to 56.1%,pressure pulsation amplitude locate at D1 decrease significantly,and the flow state in internal flow field is better,especially the flow state in diffuser.3.On this basis,by comparing the curve of head and efficiency changing with flow from steady numerical simulation in model pump,double tongue and bionic volute pump,the different performance of external characteristics among three different centrifugal pumps can be get.By comparing the calculated value and experimental value of pressure fluctuations on the absolute value in the cross section among three centrifugal pumps from unsteady numerical model calculation,thus the accuracy of the pressure pulsation characteristics can be analyzed.Under different conditions,comparing calculation value and experimental value of the mean of radial force in single tongue centrifugal pump with which in double tongue,then the accuracy of the radial force ripple characteristics can be analyzed.