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物质热力函数(摩尔定压热容、熵、焓)是用于火箭发动机热力特性分析的常用函数.根据热力学关系,上述3种热力函数可表示为以温度为自变量,且含相同7个温度系数的多项式.由于精确分析物质热力特性的需要,需要各温度下更新更精确的数据值.将热力函数按温度高低分为不同区间,在保证各温度连接点函数值相等的情况下,采用最小二乘法的数学方法,通过编程计算,重新确定了135种火箭发动机常用物质的温度系数,得到300~5 000 K内这些物质的函数计算值.进一步,对氮原子、液体铅、固体硅等相对误差较大的26种物质的摩尔定压热容利用最小二乘法再次进行了修正,使其精确度平均提高了100倍.所得到的热力函数计算值与标准值比较,误差小,精度高,使用方便,具有广泛的应用价值.
The thermodynamic functions (molar constant pressure heat capacity, entropy, enthalpy) are commonly used functions for the analysis of the rocket engine thermal characteristics. According to the thermodynamic relationship, the above three kinds of thermodynamic functions can be expressed as the temperature as an independent variable and contain the same seven temperatures Coefficient of polynomial.As the need to accurately analyze the thermal properties of the material, the need to update the more accurate data values at each temperature.Heat the thermal function according to the temperature is divided into different intervals, to ensure that each temperature connection point function is equal to the case, using the minimum Second-order mathematical method, the temperature coefficients of 135 commonly used materials for rocket motors were re-determined by programming calculations to obtain the function calculations of these materials in the range of 300 to 5000 K. Further, for nitrogen atoms, liquid lead, solid silicon and the like The errors of the molar constant pressure heat capacity of the 26 kinds of materials with large errors were corrected again by the least squares method and the accuracy was improved 100 times on average.The calculated results of the thermodynamic function were compared with the standard ones with small error and high precision, Easy to use, with a wide range of applications.