Numerical Investigation of Turbulent Premixed Combustion in a High Acceleration Field

Abstract

To guide ultra-compact combustor (UCC) engineering, simulations were conducted about turbulent premixed combustion in a high acceleration field which is called high-g combustion, along with a detailed investigation on the evolution of turbulent premixed flame in a rotating tube of stoichiometric propane-air. The rotation of the tube was mimicked by modified momentum source term in the unsteady 2D simulations to decouple the centrifugal force and the Coriolis force, the latter of which was usually neglected in previous reports. A good agreement was found between the simulation result and experimental data, along with a discovery of the phenomenon that flame speed was accelerated by the imposed acceleration field. Further study indicated that the flame acceleration phenomenon can be attributed to the flame corrugation induced by the Rayleigh–Taylor instability (RTI). The Coriolis force was found to be non-negligible in high-g combustion since the Coriolis acceleration could be at the same magnitude as the centrifugal acceleration, and the observed flame speed was nearly 20% lower without the Coriolis force. The current study revealed that the high-g combustion in an open chamber due to the absence of pressure wave/flame front interaction could not be fully compatible with predictions derived from closed chamber experiments and that the Coriolis force could not be ignored in the high-g combustion process.