Study On Optimal Design Of The Gap Inducer For A Low-specific-speed High-speed Centrifugal Pump

To improve the cavitation performance of the low-specific-speed high-speed pump,the addition of an inducer in front of the main impeller is a common method.In this paper,a new slit inducer matched with an existing the low-specific-speed high-speed pump impeller is designed by applying binary theory,and the optimized design is completed by combining orthogonal test design and numerical simulation.The main tasks of the full text are as follows:(1)In this paper,CFTurbo is used to complete the hydraulic design of the normal inducer to match the impeller of the low-specific-speed high-speed pump,Solid Works is used to model the full flow path of the centrifugal pump in 3D,ICEM-CFD is used to delineate the computational domain and ANSYS-CFX is used to simulate the internal flow field values.The numerical simulation results of the head-flow,efficiency-flow and cavitation characteristics curves of centrifugal pumps with inducer are in agreement with the experimental results,proving the reliability of the numerical simulation method chosen in this paper.(2)The effect of seam opening parameters on centrifugal pump performance was investigated using a numerical simulation method after orthogonal test design and validation.The results show that.Influence on the head as follows:Tilt angleθof slotted,deflection angleΦof slotted,length h of slotted,width b of slotted;influence on the efficiency as follows:Φ,θ,h,b;influence on the cavitation margin(0.6Q_d)as follows:b,Φ,h,θ;influence on the head of inducer as follows:Φ,h,b,θ.With the goal of reducing NPSHr under low flow rate,the seam opening of the inducer was optimized,and the best seam opening parameters were b=1 mm,Φ=90~o,h=8 mm,θ=35~o.Numerical calculations show that the critical cavitation margin of a centrifugal pump with an optimized slit inducer is further reduced from 0.83 m to 0.7907 m in the small flow condition compared to a centrifugal pump with a normal inducer.(3)Comparative analysis of the full-runner flow field of the low-specific-speed high-speed pump with a normal inducer and the optimized design of the gap inducer shows that:the reverse jet generated by the open seam inducing wheel increases the suction surface pressure,reduces the exit of the inducing wheel vacuole area when severe cavitation,improves the stability of the flow,in basically without affecting the centrifugal pump head and the efficiency of centrifugal pumps broadens the range of conditions under which they can work steadily.