Effect of elevated pressure in the multi-scale behavior of turbulent ammonia/hydrogen/nitrogen-air premixed flames*

Spectral behaviors of turbulent ammonia/hydrogen/nitrogen-air premixed flame at different pressures are investigated to understand the effect of elevated pressures. We analyze datasets from direct numerical simulations at 1 atm and 10 atm with high mean shear velocities. We calculate the spectral densities derived from density weighted two-point correlation function defined by (Kolla et. al. JFM 2014) of scalar variance and turbulent kinetic energy (TKE). Product- and reactant-species and TKE exhibit  k^-5/3 scaling where heat release rate is maximum at both pressures. However, intermediate species such as OH and HO₂ exhibit k^-5/3 region only at 1 atm. Also, TKE spectra show a stronger contribution in the dissipation range at 10 ATM. In this presentation, we will examine the causality of the scaling for intermediate species and TKE which exhibits unique multi-scale behavior at elevated pressure by performing spectral analysis of transport equations.