Validation of classical mixing rule coupled with van der Waals type equation of state for sound speed of non-ideal gas mixture*

In the CFD analyses for the combustion chamber of liquid rocket engine, classical mixing rule (CMR) has been often applied to van der Waals (vdW) type equation of state (EOS) such as Soave-Redlich-Kwong (SRK) EOS for prediction of the thermodynamic properties of non-ideal gas mixture. However, the CMR has hardly been validated because of the lack of experimental data. In the present study, for validation of the CMR coupled with SRK EOS for sound speed, which is important to compute the flow field in the combustion chamber, we applied molecular dynamics (MD) method to a Lennard-Jones fluid with modified Lorentz-Berthelot rules that simulates oxygen-hydrogen gas mixture. For the computation of sound speed, NVEPG ensemble proposed by Meier and Kabelac (Meier, K. and Kabelac, S., J. Chem. Phys., 2006.) was employed. As a result, the sound speed from the CMR coupled with SRK EOS agreed with that from MD simulation: it was suggested that the CMR can be applied to sound speed of oxygen-hydrogen mixture system in supercritical condition corresponding to the inlet region of combustion chamber.