Effects of pressure on the dynamics of spectral kinetic energy in turbulent premixed flames

Turbulent premixed flames observed in combustion devices exhibit the presence of highly nonlinear and multiscale flame-turbulence interactions. Such devices are usually operated at high pressure to attain higher efficiency, compact design, and better emissions, which increases the complexity of flame-turbulence interactions. Therefore, an improved understanding of such interactions at high pressure is key for reliable modeling of such flames. The energetics of turbulent flow in such flames is affected by the heat release and the associated thermal expansion. In this study, we examine the effects of pressure on the dynamics of spectral kinetic energy transfer. We analyze direct numerical simulation datasets corresponding to an initially laminar methane/air premixed flame interacting with decaying isotropic turbulence. Specifically, four cases are considered to assess the effects of an increase in pressure from 1 atm to 10 atm for fixed turbulence characteristics and the effects of changes in the characteristic velocity and length-scale ratios pertaining to the flame-turbulence interactions at 10 atm. The two-dimensional spectra conditioned on the spatially averaged progress variable are examined across the flame brush. Additionally, the spectra of terms in the transport equation of the spectral kinetic energy corresponding to the advective processes, the pressure gradient effects, and the viscous effects are also analyzed to explain the behavior of spectral kinetic energy.