Numerical Simulation Of Pressure Pulsation Characteristics And Modal Analysis In The Centrifugal Pump With Inlet Guide Vane

The pre-whirl influence of inlet guide vane can not only influence the efficiency of rotators but also impact the operation stability.For the successful application of inlet guide vane(IGV)in compressors and fans,a set of symmetrical straight vane is designed for a centrifugal pump of IS150-125-250 to study the influence of different IGV numbers and pre-whirl angles on the centrifugal pump hydraulic performance and pressure pulsation characteristics,which is added in the IS150 centrifugal pump imported segment,and the modal analysis of the impeller is completed.The influence of pre-whirl angles with 6 blades of IGV on the hydraulic performance of the pump and pressure pulsation characteristics is analyzed.Study shows as follows: positive pre-whirl angle condition could improve the centrifugal pump head while positive pre-whirl angle caused head decrease.Besides,with the negative pre-whirl angle increasing,the flow rate where the highest efficiency appears shows the tendency moving to the large flow rates and the flow rate with the highest efficiency has the tendency moving to the low flow rates under positive pre-whirl angle condition.The analysis by time domain method and frequency domain method shows that the pre-whirl angle of-15° has the lower pressure pulsation amplitude and power spectral density of the main frequency compared with other pre-whirl angle conditions.And then pre-whirl angle of IGV is set as 15°,different blade number of IGV on the hydraulic performance of the pump and pressure pulsation characteristics are studied.Centrifugal pumps with more blades of IGV have higher efficiency.To take the head and efficiency into all consideration,the centrifugal pump installed with 6 blades has better hydraulic performance.Simulation results also imply that the inlet guide vane with 6 blades has lower power spectral density of main frequency on several flow rates.However,it leads to pressure pulsation amplitude increase.The static structure analysis and model analysis of the impeller are competed by ANSYS finally.Simulation shows the place where maximum equivalent stress and most total displacement occur is located at middle of the blade inlet edge closed to the tongue.And the middle position in the blade outlet edge is also found to have total displacement extreme value and equivalent stress extreme value while the rim and hub have low total displacement and equivalent stress value.The impeller of the pump with 30°pre-whirl angle of IGV has the maximum total displacement of 4.0×10-3 mm and maximum equivalent stress 9.8 MPa under design condition,which is the minimum among all the studied pre-whirl angles of IGV with 6 blades.the impeller of the pump with IGV 6 blades of IGV has the maximum total displacement of 4.4×10-3 mm and maximum equivalent stress 10.4 MPa under design condition,which is the minimum among all the studied blade number of IGV with 15°pre-whirl.By modal analysis,six order modal frequency and vibration mode are calculated.The natural frequencies of the impeller and rotating frequency(24.17 Hz)harmonics are far from the same.As a result,resonance vibration of the impeller can rarely happen.