The Rayleigh Criterion is a common measure used to quantify the stability of thermal systems. Typically the Rayleigh Criterion is expressed as the correlation between unsteady pressure and unsteady heat release where an in-phase combustion response leads to driving of instabilities. This expression however, is defined under the guise of an isentropic flow where entropy generation due to irreversibilities in combustion processes or viscous and thermal dissipation are neglected. This is largely untrue in reacting flows. The impact of entropy generation due to unsteady combustion is shown to be significant. The implications of a non-negligible unsteady entropy field leads to a generalization of the Rayleigh Criterion as well as the emergence of several combustion related driving mechanisms commonly omitted from stability analysis.
展开▼
