Bok Jik Lee
Motivation and Objectives
Combustion-based power generators in small dimensions have advantages over batteries in favor of their high power density. One of the main challenges is the difficulty in flame stabilization in the combustor with a high surface-to-volume ratio. Bluff-body flame holder is one approach to promote combustion stability. In this project, high fidelity simulations are conducted in order to understand the fundamental mechanisms of flame stabilization and blow-off behind a bluff body. Advanced analytical diagnostic tools are utilized to identify and characterize the blow-off and re-attachment processes.
Direct numerical simulations solve fully compressible multi-species reactive Navier-Stokes equations with high order explicit discretization in space and explicit integration in time, with detailed chemical kinetics. Robust non-reflecting Navier-Stokes characteristic boundary conditions are employed for both inflow and outflow boundaries. A square-shape bluff-body is computationally represented by a set of logical sub-blocks.
Highlights of Results
At near-blowoff inflow velocity, periodic local extinction and recovery of flame is observed.
Local extinction occurs near the downstream end of the recirculation area behind the bluff-body.