活塞压力计压力形变系数的理论分析

Theoretical analysis of pressure distortion coefficients for piston pressure gauges

活塞压力计作为压力测量的标准器被广泛使用,其压力形变系数是活塞压力计不确定度的主要来源之一。近年来,新型结构的活塞组件不断出现,他们的压力形变系数却没有合适的计算公式计算。该文应用弹性力学基本方程,对受内外压力和轴向压力的厚壁圆柱筒进行应变分析,得到活塞筒和活塞杆的径向位移通用表达式,并将该表达式应用于典型结构活塞组件的压力形变系数计算公式推导,公式计算的结果与已知实验数据在误差允许范围内相一致。该文活塞压力计压力形变系数公式的推导方法,为确定新型结构活塞的压力形变系数提供一个简单可靠的工具。

The piston gauges are extensively used as pressure measurement standards and the pressure distortion coefficients are the main sources of their uncertainty.In recent years,more and more new structure piston cylinder units were designed,but there are no suitable formulae to calculate their pressure distortion coefficients.In this paper,analysis of strains of thick-wall cylinder under radial and axial pressure is done by use of the fundamental equations from elasticity theory and the general expressions of radial displacement at any point in the cylinder and piston are derived.The formulae to calculate the pressure distortion coefficients for typical structure PCU are derived by means of the radial displacement expressions.The calculated pressure distortion coefficients by those formulae are in good agreement with the known experimental data under the uncertainty claimed.The method to derive the formulae for calculating the pressure distortion coefficients given in this paper provide a simple and reliable tool to estimate the pressure coefficients for new designed PCU.