Computational study of combustion characteristics and flame stability of a cavity-stabilized burner


A fundamental understanding of the stabilization mechanisms of a flame within very small spaces by the
cavity method is of both fundamental and practical significance. However, the precise mechanism by which the cavity method generally provides increased flame stability remains unclear and warrants further study.
This study relates to the combustion characteristics and flame stability of a micro-structured cavity- stabilized burner. Numerical simulations are conducted to gain insights into burner performance such as temperatures, reaction rates, species concentrations, and flames. The effects of different design parameters on flame stability are investigated. The critica factors affecting combustion characteristics and flame stability are determined. Design recommendations are provided. The results indicate that the inlet velocity of the mixture is a critical factor in assuring flame stability within the cavity-stabilized burner. There is a narrow range of inlet velocities that permit sustained combustion within the cavity-stabilized burner. Fast flows can cause blowout and slow flows can cause extinction. There exists an optimum inlet velocity for greatest flame stability. The combustion is stabilized by recirculation of hot combustion products induced by the cavity structure. The thermal conductivity of the burner walls plays a vital role in flame stability. Improvements in flame stability are achievable by using walls with anisotropic thermal conductivity. Burner dimensions greatly affect flame stability. Burners with large dimensions lead to a delay in flame ignition and may cause blowout. Heat-insulating materials are favored to minimize external heat losses. There are issues of efficiency loss for fuel-rich combustion cases.

Junjie Chen