水蒸汽密度及其偏导数的综合函数生成法

Combined Function Generation of Water and Steam Density and Its Partial Derivatives

介绍一种基于数表插值的水蒸汽密度及其偏导数的综合函数生成方法．其特点是将水蒸汽从过冷水、湿汽到过热汽，从亚临界到超临界各区域的密度及其偏导数统一规划为以压力和焓为自变量的函数形式表达，有效地解决了函数复制精度与插值数表节点设置密度的矛盾，能准确反映相变线处函数特性．通过数据预处理和函数变换等途径，提高了计算速度．

A combined method to generate functions of water and steam density and its partial derivatives is described in this paper. The advantage of the method is to combine the properties' calculation of water and steam in different regions, including liquid water, wet steam and superheated steam, into one subroutine with the same arguments. Based on analysis of the characteristics of functions to be calculated, different forms of data tables and interpolaton methods are used so that the accuracy and computing speed are increased significantly while the limited memory size is still maintained.