Research On Drag Reduction And Flow Field Characteristics In Non-smooth Surface Centrifugal Pump

As a general-purpose hydraulic machine,centrifugal pumps are widely used in industry,agriculture,and daily life;however,there is still much room for improvement in reducing energy consumption.On the one hand,with the development of industrial technology,traditional improvement methods have been difficult to meet the needs of further improvement of centrifugal pump performance;on the other hand,in terms of flow drag reduction,the emerging bionic non-smooth surface drag reduction technology has been widely used in fire protection systems,Urban sewage systems,ships and underwater weapons and many other fields.Therefore,inspired by the predecessors,this paper attempts to use the non-smooth surface drag reduction technology to arrange it on the surface of a horizontal single-stage centrifugal pump blade and study its hydraulic and unsteady flow characteristics.The specific research content of this paper is as follows:First,in order to ensure the integrity of the research,at the beginning of the research,particle image velocimetry(PIV)was used to study the single-stage horizontal transparent centrifugal pump on a smooth impeller surface.The influence of the rotational speed on the flow field characteristics of the impeller flow channel and the volute is studied.Through this part of the experimental research,the internal flow law of the centrifugal pump is mastered,and experimental data is provided for subsequent numerical simulation research.Secondly,the numerical simulation method is used to simulate the centrifugal pump on the smooth impeller surface.Firstly,the fluid domain model of single-stage centrifugal pump was established,and the meshing and irrelevance verification were carried out.Secondly,the three-dimensional steady-state calculation of the flow in the centrifugal pump was carried out by the finite volume method,and the flow characteristics under the experimental conditions were analyzed.The external characteristics such as lift and efficiency are compared with the experimental results.Finally,based on the steady-state study,the transient calculation of the flow in the centrifugal pump is carried out,and the pressure pulsation of the impeller area and the volute area is studied.The results were compared with the experimental results.Through this part of the study,the prototype pump numerical simulation method is established and verified for subsequent applications.Thirdly,based on the above experimental and numerical simulation studies,the numerical simulation method is used to design the bionic non-smooth groove structure parameters of the impeller surface.Firstly,the slab is used as the object,and the groove structure is applied to the surface to calculate the flow field.The accuracy of the calculation method is verified by comparing with the existing formula of the existing plate flow resistance.Then,based on the bionic design criterion,the centrifugal pump is fully considered.Fourthly,based on the finite volume method,the numerical simulation is carried out to study the unsteady characteristics of the centrifugal pump hydraulic performance,pressure pulsation and impeller transient stress on the impeller surface with "U-shaped" and "V-shaped" groove structures.Firstly,the steady-state calculation is carried out,and the influence of different groove parameters on the external characteristics such as the lift and efficiency of the centrifugal pump is compared and analyzed.Secondly,the non-smooth groove is analyzed by setting the pressure pulsation monitoring points in the impeller and the volute.The influence of the design parameters of the trough unit on the pressure pulsation amplitude at the main characteristic frequency of the impeller is analyzed.Finally,the drag reduction mechanism generated by the groove structure applied to the impeller surface is explored through the analysis of the flow field variation characteristics.