Research On Flow-induced Vibration And Noise Of Centrifugal Pump And Optimization Design Of Vibration And Noise Reduction

As an important fluid machinery,pump is widely used in life and work.Fluid machinery inevitably produces noise during operation,and noise pollution will seriously affect the quality of human life.Centrifugal pump is a kind of pump with low specific speed and it has been widely used in petroleum,electric power,metallurgy,chemical industry,chemical fertilizer,coal and building materials.The flow of fluid in centrifugal pump with pipeline will produce strong flow noise and strong vibration of pump body and pipeline structure.The noise pollution of pump has become a focus in application.At present,there are many researches on the internal and external acoustic characteristics of centrifugal pump,especially the flow noise,but there is little research on the external acoustic characteristics of pipeline system under the action of centrifugal pump flow field.How to reduce the pipeline noise under the action of special flow field has become an urgent problem to be solved.For the unsteady flow field of centrifugal pump and pipeline system,a study with experimental and simulation on a centrifugal pump and pipeline system with specific speed of 23 is carried out.Firstly,the steady and unsteady flow field of centrifugal pump and pipeline system are simulated,and the characteristics of pressure distribution,velocity distribution and pressure pulsation of the internal flow field of centrifugal pump body and pipeline system are analyzed in detail.The periodic interaction between impeller and tongue is the main cause of pressure pulsation on the wall of centrifugal pump.The pulsation peak is mainly concentrated at the blade passing frequency(BPF)and its frequency doubling,among which the frequency doubling peak below 3BPF is the most obvious.The characteristics of pressure pulsation in the pipeline system are similar to the pump body.With the gradual increase of flow,the impact of flow field in the transition zone of elbow increases sharply,and the changes of fluid pressure and velocity become more and more intense.For the optimization of internal flow field leading to pipeline vibration,a perforated plate elbow structure to improve the internal flow field is designed.By analyzing and comparing the changes of internal flow field and the characteristics of external sound field before and after optimization,the maximum sound pressure level is reduced from 59.8db to 44.5db,with a reduction range of 25.6%,which verifies the effectiveness of the designed optimized structure in vibration and noise reduction.For the optimization of the structural vibration of pipeline,a kind of pipeline structure with three constraints is designed according to the modal analysis results,and the constraint position of the designed pipeline constraint structure is automatically optimized by using the improved genetic algorithm and taking the position parameters of the three constraints as the design parameters.The final optimization results show that the optimization effect is the best when the constraint positions are 120 mm,118mm and 62 mm respectively.Compared with the unconstrained structure,the sound pressure level of the optimized structure is reduced by 29.2%;Compared with the initial constrained design,the sound pressure level of the optimized structure is reduced by 11%.The effectiveness of the improved genetic algorithm in sound field optimization is further verified by comparing and analyzing the sound pressure level cloud map and polarity map.Through the above research content,it can verify the feasibility of the optimized structure and intelligent optimization method proposed in the field of sound field,and can achieve good results.The research results have great reference value for the collaborative optimization of multiple physical fields in other fields.