Numerical investigation of effects of pressure and chemistry on characteristics of turbulent premixed flames

Turbulent premixed flames are used in many energy conversion and propulsion devices. The efficiency and performance of these devices are affected by operating conditions, which also affect the highly nonlinear turbulence-chemistry interactions (TCIs). Previous fundamental studies characterize TCIs at atmospheric pressure, but relevant devices usually operate at higher pressures. This study investigates the effects of elevated pressure and finite-rate chemistry on methane/air turbulent premixed flames using direct numerical simulations performed at pressures of 1 atm and 10 atm and utilize an 8-species and 4-steps mechanism and a 13-species and 73-steps mechanism. The effects of pressure and chemistry on TCIs are examined in terms of the statistical and spectral features. At elevated pressure, there is more flame-front wrinkling, affecting flame curvature and heat release rate. The smaller length scales of turbulence become more energetic, and TCIs are more sensitive to finite-rate chemistry, indicating that complex chemical models may be more appropriate