The Thermodynamic Regime During Mixing under High-Pressure Conditions

Abstract

Injection and mixing of high-pressure multi-species mixtures are critical processes for several practical systems used in automotive and aerospace industries. Examples include diesel engines, gas turbines, and liquid rocket engines; in all of these devices the pressure of either the fuel or the oxidizer is above critical pressure. To control combustion in the chambers of these engines, one must control the processes of fuel penetration, mixing of reactants and the timing of ignition. The actual control very much depends on the thermodynamic regime of the mixture. Thus, in this study we inquire about the thermodynamic regime of complex mixtures injected in combustion chambers and use the spinodal locus as discriminant to distinguish between single-phase and two-phase regimes. A mathematical formalism is used to first compute spinodal locus for mixtures for which either experimental data or previous computations are available. and it is shown that there is good agreement between the results of the present calculations and that previously existing information. Further, the methodology for computing the spinodal locus is here applied to surrogate diesel fuels. According to these calculations, diesel fuel surrogates are always in the single-phase regime at injection-conditions pressures and temperatures existing in diesel engine combustion chambers.

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