| Hydraulics is the foundation of the people's livelihood,is the lifeblood of agriculture,is the cornerstone of social progress,water purrps and pumping station is the important driving force of the development of water conservancy.Axial pumps are widely used in various fields in terms of their low occupancy height and the ability to provide large flow of water,but the performance of the pump device can't meet all the needs of the industry.In order to maximize the performance of axial flow pump,the study of axial flow pump components optimization has never stopped.The water outlet pipe has always been a very typical complex flow problem in fluid mechanics.The outlet pipe has an obvious effect on the efficiency of the pump unit.It changes the flow direction of the pump and the fluid flow inside the pipe becomes more disordered.The outflow fluid from the impeller chamber causes the secondary flow in the outlet pipe to become more complicated under the influence of the ring volume,and it is very difficult to optimize its performance.However,the research on the flow in the outlet pipe at home and abroad has never been studied Stop,outlet pipe as an essential part of the pump unit,to optimize it is imperative.This paper focuses on the effects of the different optimization directions of the components of the axial flow pump.The main research contents and achievements are summarized as follows:The RNG k-? model with better accuracy and better reliability is used to simulate the pump section of different design schemes.The performance and flow regime of the pump section are analyzed and compared with the flow characteristics of the outlet pipe.(1)Compared the performance of large diameter elbow and small diameter elbow in the efficiency,head,hydraulic loss,uniformity of export speed,pressure recovery capacity of the merits of the situation,while comparing the two in the flow of different.There are no significant differences in the effciciency and head performance of the pump section with different schemes,but the hydraulic loss of the small diameter pipe is smaller relative to the large diameter pipe and the flow regime is relatively stable.The area where the flow is stable at the exit of the pipe is mainly about one fifth of the diameter of the pipe wall.The inner fluid is in a spiral state to the side of the pipe,and the other side of the rotation is not obvious,and the rotation velocity is stronger side of the wall side.It can be seen from the impeller and guide the flow of fluid through the elbow when the elbow in the circumferential and radial flow velocity weakened close to the wall quickly through the elbow and the water,and the fluid in the inner side is kept in a spiral state through the elbow.(2)The hydraulic performance and flow regime of small diameter elbow at different diffusion angles are compared.The size of each part of the parts is analyzed and the modeling is done by expanding the outlet pipe into a flow path.After the simulation,it was found that the pump section efficiency and the head change performance were stable and the water loss of the water pipe was small when the diffusion angle of the outlet pipe was within 4 degrees.However,the flow distribution of the outlet pipe at the angle does not change significantly at all angles,and the effluent elbow with the diffusion angle of 3 degrees is the best.(3)The performance and flow performance of the outlet pipe at different outlet cross sections were compared.The method is to reduce the cross-sectional height of the small diameter bend with a diffusion angle of 3 degrees.Comparative analysis found that the outlet pipe with a height of 302mm to 308mm is more advantageous in terms of performance and flow.(4)The paper analyzes its performance and flow trends after reduces the overal height of the outlet pipe.Reduced height refers to the decrease in elbow height along the exit section,and the overall height reduction is bound to cause the elbow center axis to be not the original axis of the standard 60 degree elbow.After determining the position of the inlet and outlet center points,use the UG to do the cubic spline curve while keeping the vertical axis of the elbow at the inlet and outlet sections.The cubic spline is the central axis.After numerical simulations,it was found that reducing the overall height would only degrade the overall performance and increase the hydraulic loss of the elbow and become more and more disordered in the flow regime.The spiral state of the fluid in the lower part of the elbow is more intense,and the circumferential and radial velocity of the spiral region increases gradually,and the variation rate is increasing.The research in this paper combines various indicators to measure the performance of the pump,and obtained the performance data and flow performance data of the different schemes of the axial flow pump which provides the necessary research data for the optimization of the effluent elbow.By comparing the advantages and disadvantages of the various schemes in performance and flow conditions,it provides a reference for the optimization of the effluent elbow of the axial purrp. |
PDF Full Text Request