不同温度条件对加油机金属量器检定结果的仿真分析

Simulation Analysis of Verification Results of Fuel Dispenser Metal Measuring Vessel under Different Temperature Conditions

  • 摘要: 加油机现场检定常以20 L、50 L金属量器作为工作基准,但薄壁不锈钢量器随温度热膨胀会改变刻线对应容积,使环境温度波动转化为示值误差,该文以20 L与50 L量器实物与关键尺寸为依据建立不锈钢(304)三维参数化模型,在0~40 ℃范围内按5℃梯度设置温度工况,采用热-结构顺序耦合有限元方法计算温度场、热变形与容积漂移并将容积偏差等效传递至检定误差。结果表明:在均匀温度场下,两种量器容积随温度近似线性,20 L量器容积灵敏度约1.02 mL/℃,50 L量器约2.55 mL/℃;当温度由20 ℃升至40 ℃时容量分别增加约20.4 mL与51.0 mL,若仍按20 ℃标称容积判定将引入约0.102%的系统偏差。考虑三点支撑约束与顶部/侧壁换热差异后,过渡区出现位移梯度非均匀温度场,使同一环境温度下的容积额外偏离0.2~3.1 mL。基于敏感区贡献提出两点测温等效温度修正模型,可将附加偏差压缩至毫升级,为现场温度控制、测温布点与量器修正提供可操作的定量依据。

     

    Abstract: Field verification of fuel dispensers usually adopts 20 L and 50 L metal measuring vessels as working standards. Thermal expansion of thin-wall stainless steel vessels under varying temperatures changes the volume corresponding to scale marks, and environmental temperature fluctuations are converted into indication errors. Based on the physical prototype and key dimensions of 20 L and 50 L measuring vessels, a three-dimensional parametric model of 304 stainless steel is established in this paper. Temperature working conditions are set at 5 ℃ intervals within the range from 0~40 ℃. The thermal-structural sequential coupling finite element method is applied to calculate temperature field, thermal deformation and volume drift, and volume deviation is equivalently transferred to verification error. The results show that the volume of both measuring vessels varies approximately linearly with temperature under a uniform temperature field. The volume sensitivity of the 20 L vessel is about 1.02 mL/℃, and that of the 50 L vessel is about 2.55 mL/℃. When the temperature rises from 20~40 ℃, the volumes increase by approximately 20.4 mL and 51.0 mL respectively. Judging results according to the nominal volume at 20 ℃ will introduce a systematic deviation of about 0.102 %. After considering three-point support constraints and the heat transfer difference between the top and side wall, a non-uniform temperature field with displacement gradient appears in the transition zone, which causes an extra volume deviation of 0.2~3.1 mL at the same ambient temperature. A two-point temperature measurement equivalent temperature correction model is proposed according to the contribution of sensitive zones. This model can reduce the additional deviation to the milliliter level and provides operable quantitative reference for on-site temperature control, temperature measuring point layout and measuring vessel correction.

     

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