Modeling of chemical equilibrium is fundamental to the analysis of rocket motors. Related modeling supports performance calculations, combustion gas properties, and important interactions between reactive gases and ablative insulators. Available computer programs for providing these types of calculations were primarily developed decades ago and are known to have solution instabilities and limited capabilities. The authors have previously presented mathematical solution methods for determining compositions of systems in chemical equilibrium. Here, the methodology is extended to include calculations for thermodynamic properties. This requires certain modeling assumptions and complex calculations to determine composition derivatives. Detailed derivations are provided so that modeling assumptions and property definitions are clear, and all mathematics are presented in matrix–vector form to support program implementation using modern programming methods. This methodology has been implemented into a computer program named Chemics, and verification of this approach and implementation is presented here by demonstrating accuracy against property data for air over a wide range of temperatures and by comparing thermodynamic property calculations for the combustion products of an aluminized propellant against results using a legacy modeling program. The Chemics program provides a modern platform for equilibrium calculations, extends applicability, and improves stability over legacy programs. Continued development is underway to provide advanced implementation into rocket performance and ablation heat transfer modeling programs.
Thermodynamic Property Calculations for Equilibrium Mixtures
Journal of Thermophysics and Heat Transfer ; 32 , 1 ; 118-128
2018-01-01
Article (Journal)
Electronic Resource
English
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