Characteristics Analysis Of Axial Flow Pump Mechanical Blade Fully Adjustable Mechanism And Its Application

Axial flow pump has the characteristics of narrow zone of high efficiency and instability of small flow area.When the water level or lift of the pump station changes greatly,deviating from the rated condition,not only the pump device has low efficiency,large energy consumption,and is prone to vibration,overload,Cavitation and other phenomena,affecting the durability of pump units.Condition adjustment is the pump unit to adapt to operating conditions,to ensure efficient and safe operation of an important means.Axial flow pumps are mainly vertical.Large and medium-sized axial flow pumps are mostly equipped with mechanical full-blade adjusting mechanism.By changing the impeller blade angle,the operating conditions of the pump are changed to achieve the goal of high-efficiency and safe operation.At present,mechanical blade full adjustment mechanism force and deformation,angle adjustment error is not clear,and often fails.In this paper,the mechanical composition of axial-flow mechanical full blade adjusting mechanism and its influencing factors are analyzed.Taking a vertical axial-flow pump as an example,the stress and deformation of the adjusting mechanism with different lift and angle conditions are analyzed in detail.The error of blade angle adjustment under different working conditions was calculated.The cause of bearing failure of adjusting mechanism was analyzed.Countermeasures and measures were put forward to reduce the adjusting force,improve the adjusting accuracy and improve the reliability and durability of adjusting mechanism.The main contents of the research and innovative achievements are as follows:(1)The mechanical adjustment mechanism of vertical axial flow pump blades is formed by the blade water moment,the blade centrifugal moment,the sealing moment of the blade root and the gravity of the adjusting rod.(2)The establishment of 3D model of axial flow pump before and after the extension.Turbogrid software is used to mesh the fluid field of impeller and guide vane.Gambit software is used to mesh the front and back extension fluid fields.CFX software is used to calculate Pump internal flow field,the pressure distribution of impeller blades and the hydraulic moment relative to the blade axis under different working conditions of different devices and different working conditions were analyzed.The pressure distribution law and the variation law of hydraulic moment under different working conditions were analyzed.(3)The centrifugal moment of blade and the friction torque of root seal at different blade angles were calculated.Considering the hydraulic moment of the blade,the centrifugal moment,the friction torque of the root seal and the gravity of the adjusting rod,the force analysis of the blade adjusting mechanism was carried out.The intensity check was carried out,and the regulation of adjusting force with working conditions was analyzed.Considering the size and pulsation of the adjusting force in different adjusting directions,the bearing and the bearing life of the adjusting mechanism are predicted,and the lower bearing of the adjusting mechanism in the actual operation is verified to be more likely to fail.(4)The relationship between blade angle and adjusting rod and cross stroke is deduced.The display error of blade angle caused by the deformation of the adjusting mechanism and bearing clearance is calculated.The influence of adjusting error on the performance of the pump is analyzed.(5)It is proposed and realized that by optimizing the position of impeller blade axis,the maximum water moment of single leaf in pump operating range can be reduced.By improving the blade root seal to reduce the friction torque,the use of a smaller angle of thrust thrust bearing to reduce the bearing surface pressure,to reduce the adjustment force and angle adjustment error,can improve the accuracy of adjustable angle and adjust the mechanism of durable durability the goal of.In this paper,by calculating and analyzing the force and adjusting error of the mechanical adjusting mechanism of the axial-flow pump,improving the adjusting angle and prolonging the service life of the adjusting mechanism are putting forward.Flow pump and guide vane mixed flow pump is widely used to promote the progress of the industry,of great significance.