Numerical estimation of blowout, flashback, and flame position in MIT micro gas-turbine chamber

摘要

Combustion of hydrogen-air mixture has been simulated numerically inside the MIT (Massachusetts Institute of Technology) micro gas-turbine chamber. Blowout, flashback, and flame position have been studied for different equivalence ratios. Some of the considerations in this simulation are applying a 9-species, 19-step hydrogen-air reaction mechanism, thermal coupling of reacting flow and solid structure of the combustor, considering radiation and convection heat loss from the outer surface of the combustor, and exerting physical boundary conditions on 3D geometry of the combustion chamber. To solve the simulating equations for 3D computational fluid dynamics model, finite volume method has been implemented, and parallel processing has been performed on 6 compute nodes. To validate employed simulating models, the simulation results have been compared with experiment results reported from MIT laboratory and also with simulation results obtained by another research team. The comparison shows that using eddy dissipation concept model (EDC) with disabled turbulence productions and turbulent viscosity terms in k and ε transport equations and solving equations with remaining terms can predict range of mass flow for stable combustion much closer to experimental results (more than 200% improvement in simulation results), which implies that it can be considered as a relatively reliable method for modeling mean reaction rate of micro-combustion.