The Study Of Pumping Efficiency And Metrological Characteristics For Volatile Liquids During The Refueling Process

Gasoline and other volatile liquids have low pumping efficiency and measuring accuracy because of its characteristics containing low viscosity and easy vaporization. This paper investigated the pumping efficiency and metrological characteristics based on the deep insight of volatile liquids’ physical properties, and the main content was concluded in the following.In the pumping efficiency research, this paper introduces the working principles of EPZ pump, and established an equivalent internal leakage model for the pump, and deduced a formula of volumetric efficiency and its parameters’ formulas first. Then, set up the test platform of pumping volatile liquids. Investigated the pumping characteristics and the change rules of equivalent parameters and the mechanism of equivalent leakage. Concluded the mechanism of the change in volumetric efficiency curve was the equivalent leakage flow occurring transition, and obtained the Reynolds number of flow state transforming in the equivalent internal leakage model. Next, investigated the relations between equivalent resistance coefficients and its influence factors including viscosity, overflow pressure, vane structure, inlet resistance and outlet resistance. Finally, we obtained that the cavitation was the key factor of changing volumetric efficiency through analyzing. In order to reduce the cavitation phenomenon and improve the volumetric efficiency during the pumping process, we made an optimization for the pump’s internal structure.In the measuring metrological characteristics research, this paper introduces the working principles of SM80 flow-meter, and established an internal leakage model for the flow-meter, and deduced formulas of measuring accuracy when the flow regime was laminar, turbulence or transition respectively first. This models provided a theoretical basis for investigating or analyzing the pumping efficiency and metrological characteristics. Then, analyzed the change rules of measuring accuracy curves in the condition of piston clearance having leakage and without leakage. Analyzed the change rules of measuring accuracy curve, leakage-pressure curve and leakage ratio-flow rate curve. Next, for the measuring accuracy model of flow meter, we investigated the relations between measuring error and its influence factors when flow regime was laminar, turbulence and transition respectively. Finally, we optimized the piston clearance in theory and got the scope of design value based on simulation results of measuring accuracy, which would improve measuring accuracy of flow meter.