Assessment of Thermodynamic Models for Dense Gas Dynamics

The accuracy of thermodynamic models in the computation of nonclassical gasdynamic phenomena is discussed, to investigate their suitability in connection with the design of experimental apparatuses aimed at the observation of nonclassical wavefields. The Soave–Redlich–Kwong and the Peng–Robinson are preliminarily suggested as alternative thermodynamic models to the Martin–Hou usually considered in nonclassical gasdynamics of fluorinated substances. The validity of these models is assessed by comparisons to reference experimental data for fluorinated R13, R125, C318, FC-72, FC-75, and SF6 and to the Martin–Hou model itself. The three models are found to exhibit a comparable accuracy for reduced volumes ranging from 1.4 to 2.5 and near the critical isotherm, i.e., in the thermodynamic region where heavier fluorinated substances such as PP10 are expected to exhibit nonclassical gasdynamic phenomena. The Soave–Redlich–Kwong and the Peng–Robinson models are then used to supplement previous numerical results for a three-discontinuity nonclassical shock-tube experiment with fluid PP10, which was designed under the Martin–Hou model. Under the initial conditions chosen for the experiment, the three models agree in predicting the formation of a supersonic nonclassical rarefaction wave, with wave Mach number in the range 1.01–1.02, thus providing further confidence on the possibility of experimentally observing nonclassical gasdynamic behavior in fluid PP10.