Hydraulic Design Of Vortex Self-priming Pump And Bionic Optimization Of Flow Noise

The flow rate of self-priming vortex pump is low and the head is high,so its special speed pump is low.The running noise is high especially in the low flow rate operating conditions.This research object is a XKM80-1 type self-priming pump from a company in Zhejiang.Firstly,the key hydraulic components of the pump are designed according to the performance requirements.Though the numerical calculation result of the flow domain and acoustics domain gain the tongue gap is the key influencing factor on acoustic performance.Selecting the tongue gap as the object of study and using the non-smooth surface structure of the shark’s surface to do bionic design.The initial design of tongue gap is the trapezoidal shaft section and the curve cross section;gain the curvilinear cross-sectional scheme reduces the amplitude of the pressure fluctuation at the tongue gap,and the curvilinear cross section is selected to optimize the tongue gap.In order to control the parameters of curve cross section,the design of the tongue gap fluctuation structure based on the simple harmonic function.The variable parameter is the ratio of wavelength to amplitude.Finally,considering the performance of head,efficiency and maximum sound pressure level at the monitoring point,the mathematical model of comprehensive performance optimization is established,and the best performance scheme is calculated.According to the design parameters,the least squares polynomial fitting algorithm and comprehensive performance optimization mathematical model design the data processing executable program of MFC-based that using to do the data processing.The main contents of this paper are as follows:1)Numerical calculation of full flow field on acoustic and hydrodynamics.The hydraulic design completed according to performance requirements.The test performance is accordance with the requirements.The steady-state numerical calculation is in agreement with the experimental data.Large eddy simulation is used to calculate the hydrodynamics of flow field and the key points are set as the monitoring points to get the pressure fluctuation.Though the Fourier transform get that the frequency of the pulsating pressure is mainly concentrated at 1-3 times the leaf frequency and 1 times of the axial frequency.The main frequency is calculated as the acoustic calculation frequency.The internal flow field dipole noise source is derived as the excitation source to calculate the acoustic boundary element of the vortex pump.The result shows that the sound pressure level at the tongue gap of the pump is higher than that of other regions at the main frequency,so the position of the tongue gap is determined as the object of acoustic optimization.2)Surface bionic design and flow field analysis on tongue gap of the vortex pump.According to the non-smooth surface features of the shark’s epidermis,the surface of the tongue is designed as non-smooth surface.The trapezoidal section and the curve section are designed qualitatively.The LES method is used to calculate the original design scheme,the trapezoidal section and the curve section scheme.The static pressure,boundary vortex flux,eddy current and the unsteady characteristics of the vortex core area in the period are analyzed.The static pressure of the tongue monitor points obviously changed.Compared with the original design and the trapezoidal section,the curve section can reduce the amplitude of the pressure pulsation at the monitoring points,the distribution of the vortex on the wall is relatively discrete,and the distribution of the vortex flux is uniform,so it can weakened the intensity of the noise excitation source.3)Bionic design and its acoustic simulation analysis.The preliminary analysis of the flow field determines the further bionic design using the curve type,in order to controls the parameter variables of the curve and constructs of the bionic design,determines the ratio of the wavelength to amplitude as the single factor.The mathematical model is established,and the ratio of wavelength and amplitude used as independent variables to construct the single factor test sample space.The independent variables are 5.0,7.5,10.0,12.5 and 15.0 respectively.Do numerical simulation on the flow field and sound field of the designs.The head,efficiency and maximum sound pressure level at the monitoring point taken as the target parameters of the test.The results show that with the increase of the independent variables,the head is gradually reduced,compared with the original design,the results of the five groups decreased by about 5%-10% on average.The efficiency of test increased by about 3%-5% on average and the sound pressure level of the monitoring point changed greatly,when the wavelength and amplitude ratio is 5.0,7.5,15.0 the sound pressure level increased and the acoustic performance deteriorated,the ratio at 10.0,12.5 the maximum sound pressure level at the monitoring point decreased by about 4.8 d B,5.75 dB.4)Data analysis and processing.The least squares method is used to fit the polynomial between the target parameter and the independent variable,and the goodness of the fit is guaranteed to be above 0.9.The relationship between the head,the efficiency and the independent variable is second-order relationship,and that of sound pressure level is third-order relationship.The performance fitting equations are given different weights and weighted sum the improvement of design to original.The calculation step is as follows: first,determine the weight of each performance.Then calculate subtract between optimized value and the original design value divided by the original design value,and obtain the dimensionless optimization value.Finally,the sum of the weighted performance is obtained.In this study,the XKM80-1 type of self-priming vortex pump is mainly optimized for acoustics performance and both charge the efficiency and head performance,so in this study the weight of the head,efficiency and sound pressure level choosing 0.2,0.3,0.5.Finally,based on the numerical calculation data and the related mathematical model,the least square method polynomial fitting algorithm is used to determine the mathematical equation of the optimization target.The data processing executable program based on MFC is designed and the data processing of the single factor multi-objective experiment is carried out.The optimum performance is about 0.5% when the wavelength and amplitude ratio is 10.