Study And Application Of Wide Range Minute Flow Measurement With Low-pressure Loss Based On Turbine Flowmeter

Automotive electronic fuel pump is one of the key parts of automobile fuel supply system. In order to meet the accurate control of the fuel injection quantity in the automotive electronic fuel injection system, the amount of oil pumping per unit time and its stability act as an important technical indexes of automobile electronic fuel pump. In the process of automobile electronic fuel pump design and production, flow is needed to be accurately measured under different fuel supply pressure. Usually, the flow rang for a general model of automobile electronic fuel pump is from 10L/h to 300L/h, which belongs to the minute flow range, and the rated operating pressure is 300 Kpa, which requires low pressure loss. However, poor linearity of minute flow or the problem of large pressure loss exist in the measurement of automotive electronic fuel pump. So the study on wide range minute flow measurement with low-pressure loss plays an important role in the electronic fuel pump production and has practical values.The thesis compared with the current flow measurement method, and points out that turbine flow measurement has the advantage of simple structure, low cost and shows better performance in minute flow measurement. Therefore, the thesis selected turbine flowmeter as the research result in order to find a flow measurement method which can satisfy the requirement of automobile electronic fuel pump flow measurement.The model of tangential turbine dynamic model is established by using the theory of Fluid Dynamics, and CFD simulation analysis, which is the abbreviation of Computational Fluid Dynamic, analysis was carried out. In the simulation process, the thesis provided the segmented simulation model method of distinguishing turbulent and laminar flow by the value 2300 as the cut off point to choose different turbulence equation models for turbine flowmeter in CFD calculation aiming at the problem of unstable coefficient K in minute flow measurement, as a result of which improved the authenticity of simulation. The moment monitoring method is put forward to find the balance of rotation speed and drive torque for equilibrium position aiming at the problem of low efficiency and bad accuracy with the existing moment monitoring method in CFD calculation of tangential turbine flowmeter model, which as a result reduced the simulate cycle and improved the accuracy.The simulation results showed that the tangential turbine model has better accuracy and smaller measuring linearity error than the axial turbine model. Therefore, a method of using tangential turbine model instead of traditional axial turbine model for minute flow measurement and a design for tangential turbine flowmeter are proposed in this thesis. According to parameters such as length of turbine blade and diameter of input nozzle, which are important in meter factor K. the thesis put forward a optimization design method and by using this method. A tangential turbine flow sensor is designed and its specific parameters are determined for one model of electronic fuel pump.Finally, experimental verification is proposed to test the minute flow measurement method by using the platform for automobile electronic fuel pump test. The experimental results showed that the method can satisfy the measuring requirement of low pressure loss, wide range in minute flow for the automotive electronic fuel pump, which reached a expected goal.