NASA polynomials computer program

FITDAT Kee, R. J., Rupley, F. and Miller, J. A. Sandia National Laboratories, Livermore, CA 94550. A Fortran computer code (fitdat.f) that is part of the CHEMKIN package for fitting of species thermodynamic data (cp, h, s) to polynomials in NASA format for usage in computer programs. 

The calculation of the heat functions [eqns 5 and 6] is not easy from the tabulated values of 0° as a function of T. It is therefore desirable to have an analytical expression available. The NASA representation used in the CHEMKIN computer program is a polynomial of degree 4 in T ... 

This computer program calculates the coefficients of the NASA polynomials from thermodynamic data supplied by the user. 

Most of the JANAF tables have been fitted to polynomials by the NASA thermodynamics group. Polynomial coefficients for the species included in the main JANAF volume (1971) have been published (Gordon and McBride, 1971) and are supplied with the NASA SP-273 computer program. 

U.S. government agencies such as NASA and National Laboratories had computers by the end of the 1950s, and therefore started using polynomials in order to get thermochemical properties as a function of temperature. The functions were needed in order to calculate equilibrium compositions of reacting mixtures, which were extensively used before kinetic simulation programs were available. This was the reason for the publication of Duff and Bauer s paper [14], which included extensive equilibrium calculations. 

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