双毛细管法高温气态环己烷黏度测量研究

Viscosity Measurements for Gaseous Cyclohexane at High Temperature by Two-Capillary Method

关键词:  双毛细管法  气态黏度  二次流效应  测量精度  再生冷却

Key words:  Two-capillary method  Vapour-phase viscosity  Secondary flow effects  Measurement precision  Regenerative cooling

摘要:

为了探索双毛细管法在碳氢燃料高温气态黏度测量中的应用，采用双毛细管法测量了亚临界压力下环己烷的高温气态黏度。测量温度为301.9~567.1K（间隔约10K）；压力为0.5~4.0MPa（间隔1.0MPa）。考虑螺旋管圈的二次流效应，使用基于雷诺数Re或迪恩数De的函数关系式对黏度测量结果进行离心修正。在测量参数条件下，气态环己烷的雷诺数Re≤1984.5。研究表明：双毛细管法测量环己烷液态和气态黏度时，螺旋管圈的二次流效应具有显著差别；液态环己烷的离心修正系数<4.32%，气态环己烷的离心修正系数最高达到49%；离心力二次流效应是影响环己烷气态黏度测量精度的最重要因素；离心修正关系式的准确度对环己烷气态黏度测量结果的不确定度产生显著影响。

Abstract:

In order to develop the application of two-capillary method on the viscosity measurement of gas hydrocarbon fuel at high temperature， the viscosities of gas cyclohexane were measured by the two-capillary viscometer at high temperature and subcritical conditions. The temperature ranged from 301.9K to 567.1K （about 10K intervals） and pressure ranged from 0.5MPa to 4.0MPa （1.0MPa intervals）. Considering the secondary flow of fluid in the coils， the viscosity measurement results were modified by centrifugal correction coefficient as a function of Reynolds number （Re） or Dean number （De）， and the Reynolds numbers （Re） of the gas cyclohexane were below 1984.5 in the measurements. The research indicated that the secondary flow effect in the coils differs significantly between the viscosity measurement of liquid and gas cyclohexane by two-capillary method. The centrifugal correction coefficients for viscosity measurements of liquid cyclohexane was less than 4.32%， for viscosity measurements of gas cyclohexane was up to 49%.Therefore， the second flow effect that results from centrifugal force is the most important factor affecting the measurement accuracy of the viscosity of gas cyclohexane， and the accuracy of the centrifugal correction function plays an important role on determining the uncertainties of measurement results of viscosity of gas cyclohexane.