Research On Flow Field And Pressure Pulsation Characteristics Of Centrifugal Pump Based On Laser Diagnosis Technology

The flow state and pressure pulsation of the internal working fluid of the centrifugal pump will directly affect the reliability,safety and hydraulic performance of the pump.By studying the pressure fluctuations in the pump and the flow characteristics of the flow field,the flow law of the working fluid can be revealed in depth,which can be centrifuged.Pump design,improvement,and vibration and noise reduction provide guidance and are of great engineering importance.Due to the complexity of the centrifugal pump structure and the internal working fluid flow,the current understanding of its internal flow law is still in its infancy.In order to further reveal the internal flow law of the centrifugal pump,it is necessary to carry out detailed research on the flow field and pressure pulsation.This subject is based on a transparent single-stage volute centrifugal pump,the main research work as followed was carried out:(1)In view of the shortcomings of the internal flow field measurement of the traditional centrifugal pump,this project uses a high-power continuous laser with a high-speed camera,and rationally arranges the pressure pulsation measuring point,and designs and constructs a visualized flow field-pressure pulsation experimental measurement system and optical path system,which can realize centrifugation.Real-time capture of flow field information and pressure pulsation information inside the pump.The measurement of the internal flow field information of the centrifugal pump is millimeter-level and the uncertainty is within 2%,which greatly improves the time resolution and accuracy of the flow field information capture.(2)Based on the time series of PIV flow field measurement technology,the refined measurement of the internal flow field of the centrifugal pump in time series is carried out,which greatly reduces the loss of flow field information in time series and improves the refinement of flow field measurement.On this basis,the internal flow field characteristics(flow field distribution,turbulence intensity,Reynolds stress and evolution of the flow field structure)of the centrifugal pump are studied in depth.The study of vortex analysis shows that the size of the vortex structure in the flow field is negatively correlated with the flow rate.(3)Through the numerical simulation study of the internal flow field characteristics of the centrifugal pump under high-speed working conditions,the shortage of the experimental measurement in the hardware condition is compensated,and the numerical simulation of the steady and unsteady flow fields is carried out,and the internal flow field distribution and flow of the centrifugal pump are Field structure evolution,dynamic and static interference have been studied in depth,revealing the characteristics of the flow field and the evolution of the flow structure.The research have shown that the generation-shedding of the internal vortex structure of the impeller is periodic,and the periodicity becomes longer as the flow rate decreases.(4)The micro-high-frequency pressure pulsation sensor was used to measure the circumferential and axial pressure pulsation of the internal flow field of the centrifugal pump.The spectral composition of the pressure pulsation in the centrifugal pump was studied in depth.The study shows that the leaf frequency is the main frequency of the circumferential pressure pulsation and mainly contributes to the non-uniform flow field structure generated by the turbulent flow at the impeller exit.The relationship between flow field and pulsation is analyzed preliminarily.The research indicates that the centrifugal pump pressure pulsation is closely related to the internal flow field distribution characteristics.The turbulence intensity of the flowing medium and the generation and development of the vortex structure are the main sources of flow noise.