Flowrate Measurement Performance Research Of Water Meter Based On Fluid Simulation And Numerical Computation

Flowrate measurement performance is a very important technical index in the development and production of water meter,and it is also a technical conundrum,which has been continuously studying in water meter industry.The thesis focuses on multi-jet impeller water meter as research object.Firstly,it analyzes the impeller's drive torque and resistant torque in the flowrate measurement process.The mathematical relationship between flowrate and impeller rotating speed based on mathematical model structured is established.By introducing the relative error of water meter,the mathematical relationships between testing error and flowrate,testing error and resistant torque are established.Moreover,water meter's flowrate measurement performance in the condition of ideal working state,starting flow state and actual working state is analyzed.Secondly,the thesis constructs fluid models of multi-jet water meter using impeller with different structural parameters,for which the 3D/2D mesh is built using ICEM CFD software,boundary and initial conditions are defined using CFX software.And it establishes impeller rotating speed,momentary and average torque of impeller as monitoring points to monitor the process convergence of simulation calculation.Moreover,it obtains some key flow field parameters in CFX post-processing,such as pressure contour,velocity contour,streamline and velocity vector,based on which flow field characteristic of important structural areas inside water meter is analyzed deeply.Thirdly,following torque equilibrium analysis method,simulated rotating speed of impeller on the steady working condition is calculated,pressure loss between inlet and outlet end of water meter is obtained using CFX solver,then it establishes corresponding relationship between flowrate and simulated rotating speed of impeller,flowrate and pressure loss of water meter.Fourthly,the thesis chiefly researches the influence of flowrate measurement performance when changing structural parameters of impeller,for example relative position,blades height,and blades diameter.Through analyzing simulated rotating speed and simulated error,it obtains influence trend of flowrate measurement performance following structure parameters of impeller,which is also verified by sample meters preparation and flowrate performance testing.Although there is some difference on error values between simulation analysis and experimental testing,influence trend of flowrate measurement performance following structure parameters of impeller is relatively consistent.Therefore,the method of flow field simulation and numerical calculation can meet the purpose of researching flowrate measurement performance of water meter,and can be considered as important means of structural design optimization.