| According to the requirements of low vibration and low noise of marine centrifugal pump,the magnetic-drive pump is designed and developed,which has the characteristics of small size,light weight,high pressure resistance,no leakage,low vibration and low noise.The design of marine magnetic-drive centrifugal pump unit adopts the vertical structure of upper motor and lower pump.The impeller is driven by cylindrical magnetic-driver,and the inner and outer magnetic rotor are isolated by isolation sleeve,which can effectively avoid the leakage of transport medium.The isolation sleeve cooling system adopts external circulation mode,and the filtration system is added,which improves the operation reliability and prolongs the service life of marine magnetic-drive centrifugal pump.The main shaft guide bearing of the pump adopts graphite bearing with inner surface lubrication groove,which can effectively improve the cooling effect and lubrication performance.In this paper the overall structure,hydraulic performance,interior and exterior acoustic field performance and unit vibration performance of marine magnetic centrifugal pump are studied by application of theoretical analysis,numerical analysis and experimental verification.The comprehensive test rig is built,which can simultaneously collect hydraulic performance,interior and exterior acoustics field and unit vibration parameters.The numerical simulation results are verified,which provides useful references for future research in related fields.The main work contents and creative achievements are as follows:1.125CLB-42 marine magnetic-drive centrifugal pump unit is designed and developed,which innovatively integrates marine magnetic-drive centrifugal pump and driving motor,besides cooling water jacket is set.In order to reduce the wind noise and mechanical noise caused by the operation of the cooling fan,the water-cooling method is used to continuously cool the driving motor instead of the traditional air-cooling method.The vibration and noise of marine magnetic-drive centrifugal pump are better than Grade A,according to the national standard.2.The whole flow field numerical model of marine magnetic-drive centrifugal pump with high accuracy is established,and the grid independence test is verified.Four different turbulence models are selected to simulate the marine magnetic centrifugal pump,and the results obtained by SST k-?turbulence model are closer to the experimental values.Under the design flow rate of 140 m3/h,the relative error of head is 1.52%.3.Four groups of different blade outlet angle models are selected to simulate and test the radial force and pressure fluctuation.The effective measure to reduce radial force and pressure fluctuation and vibration intensity is found.With the decrease of blade outlet angle,the radial force and pressure fluctuation also decrease.Under different flow rate conditions,the root mean square value of blade radial force is about 30%of impeller radial force.The main frequency of radial force fluctuation of impeller and blade is axial passing frequency(APF),while the main frequency of impeller torque fluctuation is blade passing frequency(BPF).The experimental results show that the vibration intensity of model 25 and model 35 is the highest at 0.4Q flow condition,and the lowest at 1.0Q and 1.2Q flow condition.Under the same flow rate condition,the radial vibration intensity of measuring point of volute section IV is the largest.The vibration intensity of model 25 is smaller than that of model 35.Under different flow rate conditions,the maximum vibration intensity of the two models is less than 1.25 mm/s,and the maximum vibration intensity of model 25 is only 0.97 mm/s.The main frequency of pressure fluctuation near the volute tongue is BPF,the main frequency of pressure fluctuation at the volute section and outlet is BPF,and the main frequency of pressure fluctuation at each measuring point in the impeller is 2APF.Under the design flow rate of 140 m3/h,the relative error between the simulation value and the experimental value of model 25 and model 35 is less than 6.5%.4.The numerical models of flow noise and flow induced noise in acoustic field of marine magnetic-drive centrifugal pump are established.The pump shell dipole source is extracted from the unsteady simulation of the internal flow field of marine magnetic-drive centrifugal pump,and is used as the boundary value of the radiation acoustic source of the interior and exterior acoustic field.The sound pressure level(SPL)of interior acoustic field and directivity distribution of exterior acoustic field of marine magnetic-drive centrifugal pump are studied.The analysis results show that under different flow rate conditions,at BPF and blade frequency multiplier,the SPL at inlet and outlet monitoring points have obvious 5 and 6 peaks respectively,and the SPL peak value at BPF is the largest.The acoustic radiation of the marine magnetic-drive centrifugal pump propagates to the inlet and outlet directions,and the propagation to the outlet direction is more obvious.Under different blade outlet angles,the directivity of exterior acoustic field on the same acoustic field plane has the same trend in all directions,and the extreme direction is basically the same.Under the design flow rate of 140m3/h,the SPL at BPF and 2BPF on Y=0 plane is significantly lower than that on X=0 and Z=0 plane.The maximum difference of the exterior SPL at BPF is 7.2 d B(A)and 8.0 d B(A)respectively,and the maximum difference of the exterior SPL at 2BPF is 7.6 d B(A)and 6.4d B(A)respectively.The experimental results show that the exterior SPL of model 25 is lower than that of model 35;with the increase of the flow rate,the fluctuation of the exterior SPL curve of model 25 is small,and the 1/3 octave overall sound pressure level(OASPL)of the interior acoustic field of model 35 changes little.Under the design flow rate of 140 m3/h,the maximum and minimum radiated noise of model 35 are 73.2 d B(A)and 71.5 d B(A),and that of model 25 are 72.8 d B(A)and 71.1 d B(A).The maximum and minimum radiated noise of model25 are both 0.4 d B(A)lower than that of model 35.5.According to single factor analysis,the variable factors with high sensitivity to the hydraulic performance and acoustic performance are selected,and multi-objective response surface optimization method is adopted to obtain the regression equation of efficiency and total sound pressure level with better fitting,and the optimal combination of impeller outlet diameter D2,blade outlet width b2,blade wrap angle?and blade number z is determined with the efficiency and interior acoustic field noise of marine magnetic-drive centrifugal pump as the objectives.The experimental results show that the efficiency of the optimized model is 77.2%,and is 0.8%higher than that of the original model,and the 1/3 octave OASPL of the interior acoustic field is 143.2 d B(A),and is reduced by 4.4 d B(A).In the previous literature,the main geometric parameter variables of impeller have a wide range of values,and there is great uncertainty in the design,which makes it difficult to achieve the optimal vibration and noise performance of the designed pump.The value of main parameter variables of impeller can be determined by response surface optimization.The model obtained by response surface optimization has a breakthrough in both noise and efficiency,which can effectively guide the research and design of low noise marine magnetic-drive centrifugal pump.6.According to the drag reduction principle of airfoil blade,the marine magnetic-drive centrifugal pump blade is designed innovatively with approximate airfoil.The experimental results show that under the design flow rate of 140 m3/h,compared with the original blade model,the head of the approximate airfoil blade model is 44.1 m and increased by 1.3 m,and the efficiency is 78.6%and increased by 1.1%.The 1/3 octave OASPL in the interior acoustic field is 144.5 d B(A)and decreased by 1.9 d B(A),and the maximum and minimum radiated noise in the exterior acoustic field are decreased by 1.1 d B(A)and 1.3 d B(A),respectively.The maximum radiated noise of the approximate airfoil blade and original blade models is 72.1d B(A)and 73.2 d B(A),respectively,and the minimum radiated noise of that is 70.2 d B(A)and71.5 d B(A),respectively.The results show that the approximate airfoil blade can greatly improve the hydraulic performance and acoustic performance of marine magnetic-drive centrifugal pump simultaneously,and the noise is in the leading level in the same industry.7.The influences of the extension of double volute diaphragm and the hardness of anti-vibration pad material on the hydraulic performance and vibration of the marine magnetic-drive centrifugal pump are verified.The experimental results show that under the design flow rate of 140 m3/h,compared with the model lengthened 100,the head of the model lengthened 180 is 42.8 m and increased by 0.3 m,and the efficiency is 77.5%and increased by1.5%.The 1/3 octave OASPL in the interior acoustic field is 146.4 d B(A)and decreased by 2.1d B(A),and the maximum and minimum radiated noise are decreased by 3.9 d B(A)and 2.3d B(A),respectively.The maximum radiated noise of the models lengthened 180 and 100 is 73.2d B(A)and 77.1 d B(A),respectively,and the minimum radiated noise of that is 71.5 d B(A)and73.8 d B(A)respectively.The results show that the hydraulic performance and noise performance of marine magnetic-drive centrifugal pump are improved by the extension of the volute diaphragm.With the increase of the thickness and the decrease of the hardness of the anti-vibration pad,the SPL in the interior acoustic field and the vibration intensity at the measuring points decrease.The SPL in the interior acoustic field and vibration intensity of55HA-20 scheme are the minimum.Under the design flow rate of 140 m3/h,the maximum radiated noise is 72.3 d B(A)and the minimum radiated noise is only 70.5 d B(A)in the 55HA-20 scheme,and the maximum vibration intensity is only 0.93 m/s,and the vibration intensity is in the leading level in the same industry. |
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