Study On Hydraulic Characteristics And Design Method Of Collecting Pipe Of Roto-Jet Pump

The collecting pipe stands in the liquid rotating at high speed in the rotor cavity,and its function is to convert the velocity energy of the liquid in the rotor cavity into pressure energy.The reasonable geometry and shape of the collecting pipe will improve the performance of the roto-jet pump,therefore,it is particularly necessary to study the hydraulic characteristics of the collecting pipe and its design method.In this paper,the roto-jet pump test bench was independently developed.On this basis,the effects of different relative height ratio,shape,area ratio and shape of inlet on the performance of the roto-jet pump and the flow characteristics of liquid in the collector pipe and the rotor cavity were analyzed by combining experimental research and numerical simulation.The main research contents of this paper are as follows:1.The roto-jet pump test bench and test device were independently developed,and the performance curve of the roto-jet pump with full flow conditions was tested under different inlet diameters of the collecting pipe.The test results show that under the full flow condition,when the inlet diameter of the collector pipe is d₁=15mm,the head of the roto-jet pump is higher than d₁=10mm,and it is basically the same as when d₁=20mm.The efficiency of the roto-jet pump increases first and then decreases with the increase of the inlet diameter of the collecting pipe,and the roto-jet pump has the highest efficiency when d₁=15mm.The test pump has the best performance when the inlet diameter of the collecting pipe is 15 mm.2.Comparing the performance curves of the roto-jet pump obtained by the test and simulation,the credibility of the numerical means was verified.On this basis,numerical calculations are carried out on the test pump models with different relative height ratios and different wing shapes of the collecting pipe.When the relative height ratio of the collecting pipe is 0.85,the performance of the roto-jet pump is optimal,the liquid pressure distribution in the middle section of the rotor cavity is the most uniform,the change of the turbulent energy is the smallest,and the liquid flow is better.When the shape of the collecting pipe is full-airfoil,the head and efficiency of the roto-jet pump are higher than that of the shape of the collecting pipe without airfoil and partial airfoil,and the pressure distribution of the middle section of the rotor cavity is the most uniform when the full airfoil is used,and the turbulent energy is the smallest,the liquid flow is the most stable.By studying the changes of the circumferential speed at different angles in the rotor cavity when studying the different shape of collector pipes,it can be found that the turbulence generated by the liquid shock collecting pipe has basically disappeared when it rotates one revolution in the rotor cavity and then returns to the inlet of the collecting pipe.There is basically no influence on the liquid flow at the inlet of the collecting pipe.3.In order to study the hydraulic characteristics of the collecting pipe,the numerical simulation of the experimental pump models with different inlet area ratios and different inlet shapes under full flow conditions was carried out.When the inlet area ratio of the collecting pipe is 0.14,the performance of the roto-jet pump is optimal,the pressure distribution in the collecting pipe is relatively uniform,the liquid flow is relatively stable,and the turbulent energy change is small.Introducing the dimensionless flow coefficient and pressure coefficient of the manifold,and obtaining the variation curve of the flow coefficient and pressure coefficient under different inlet diameters of the collecting pipe,which provides a new method for the study of the hydraulic characteristics of the collecting pipe.When the inlet shape of the header is circular,the performance of the roto-jet pump is better,the pressure distribution in the header is the most uniform,the variation of the turbulent energy is the smallest,and the liquid flow is the most stable.