Conditional momentum equation for modeling heat release effects on turbulence in turbulent premixed combustion*

Closure models for the conditionally-averaged momentum transport equation with respect to a progress variable have recently been developed to capture the influence of combustion heat release on turbulence in turbulent premixed combustion. In this work, a posteriori validation is performed in a spatially-evolving turbulent premixed hydrogen/air planar jet flame where heat release effects on turbulence are significant. For evaluating the conditional analog of the turbulent viscosity, a model conditional turbulent kinetic energy transport equation is solved, and an algebraic model of the conditional turbulent dissipation is utilized. Compared to conventional turbulence models, the conditional momentum equation is shown to correctly predict counter-gradient transport in low Karlovitz number turbulent premixed combustion without any a priori specification that such a phenomena should occur.