Modeling the dynamic response of a laminar perforated-plate stabilized flame

The objective of this study is to determine the transfer function between the heat release rate and the velocity oscillations in perforated-plate stabilized flames under different power and equivalence ratios. Previous planar flame models have been successfully extended to account for the conical flame surfaces formed downstream of the burner plate holes. The coupled effects of the heat loss to the burner plate and the flame kinematics have been modeled. The resonant peaks are determined by the burning velocity oscillations of the flame which arise as a result of the heat loss mechanism. Flame area oscillations become significant above the resonant frequency, introducing heat release rate oscillations and reducing the lag between the net heat release rate and the inlet velocity. The model results were compared to the experimental measurements, and good agreement is obtained. When the equivalence ratio is raised, the heat loss increases, the flame temperature drops, and the flame moves closer to the burner increasing the burner plate surface temperature and the resonant frequency. When the inlet velocity is raised, the area of the flame increases, causing substantial heat release rate oscillations at frequencies significantly higher than the resonant frequency.