| The technology of Oil and gas mixed transportation is a special technology for the development and transportation of oil and gas resources.As a device that can simultaneously transport crude oil and oil-associated gas,oil and gas mixed pumps have become the key equipment of oil and gas mixed transportation technology.Axial-flow mixed transport pump is widely used because of it‘s large transport flow,adaptability to high gas content conditions and compact structure.However,most of the structural parameters in the design of axial flow oil and gas mixed pumps are obtained based on the design experience of axial flow pumps,and may not be the best parameters for axial flow mixed pumps.This topic uses a combination of theoretical design and numerical simulation to study the effect of structural parameter changes on the performance of the compression unit of the axial flow mixed pump.The main research contents and results include:1.Research on the influence of the blade thickness along the radius on the hydraulic performance of the mixed pump.First,referring to the blade displacement coefficient,the parameter ξ is defined to characterize the area of the blade in the flow surface of the cascade.Secondly,using the parameters of the original mixed pump impeller blade and diffuser blade blades as the initial blade structure parameters,adjust the value of the cascade flow in-plane coefficient ξ of each cascade of impeller blades and diffuser blades,and inversely solve the different cascade flow-plane blade thicknesses.,And complete the establishment of the model.Finally,the numerical simulation results show that the gas-liquid distribution in the flow channel is related to the pressure gradient in the radial direction of the flow channel.The greater the pressure gradient in the radial direction in the flow channel,the more serious the gas-liquid separation;When the proportion of the blade area increases by 0.01,the pressure gradient in the radial direction of the impeller blade flow channel is the lowest,and the degree of gas-liquid separation is reduced,which is beneficial to the discharge of gas from the flow channel and improves the hydraulic performance of the axial flow oil and gas mixed pump.The efficiency is at a large flow rate.An increase of 2.1% under working conditions;when the proportion of the blade area in the flow surface of the stationary blade cascade increases by 0.01,the efficiency of the hybrid pump has little effect.2.Research on the influence of the changing law of the fixed blade installation angle on the hydraulic performance of the mixed pump.First,determine the inlet and outlet angles of the diffuser according to the velocity triangle and the non-impact condition of the inlet of the diffuser.Then,using the combination of streamline equations and Matlab software,the diffuser airfoil with linear and non-linear changes in the placement angle is obtained.The results show that the changing law of the diffuser blade placement angle has a significant impact on the gas distribution in the diffuser blade channel;numerical simulations found that: under the GVF=0.1 working condition,the hydraulic performance of the diffuser blade according to the variation law of the scheme 3 is the best.Compared with the linearly changing vane,its efficiency is increased by 1.2%;in terms of pressure load,the pressure load distribution of the vane model whose placement angle changes linearly is closer to the ideal state,and the vane whose placement angle changes nonlinearly along the axial streamline The position of the maximum pressure difference between the pressure surface and the suction surface gradually moves to the exit edge of the stationary blade as the length of the flow passage increases.3.Research on the influence of hub shape on the hydraulic performance of the mixed pump.First,according to the structural characteristics of the hybrid pump,a method for controlling the shape of the hub by the cross-section hub ratio is proposed.Then,taking the straight cone-shaped hub as the original model,under the premise of ensuring the dynamic and static inlet side hub ratio,the axial length of the dynamic and static blades and the rim radius,the five types of curved hubs are obtained by controlling the change of the hub ratio of each section.Numerical simulation results show that the gas accumulation in the flow channel hinders the axial flow of the flowing medium,and the curved hub can reduce the degree of gas obstruction;increasing the radius of the middle section of the hub can reduce the pressure gradient in the flow channel along the radius,and the inlet edges of the moving blade and the stator blade are aligned with each other.The degree of vortex and secondary flow at the outlet side are reduced,and the pressure in the stator blade flow channel increases first and then decreases.The flow of the flowing medium in the L4 model flow field is more stable,the degree of gas-liquid separation is the lowest,and the overall hydraulic performance is the best. |
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