Acoustic Alteration in a Dump Combustor Arising from Halon Addition

Abstract

The effects of halogen injection on the acoustical characteristics of a two-dimensional dump combustor are studied. The dump combustor used is one whose acoustic modes have been well characterized in prior experiments (Logan, et al., 1991). Experimental observations indicate that an increase in halon addition typically causes a slight reduction in the dominant acoustic frequency, then, at a critical percentage of halon, a switch to a higher frequency mode. It is postulated that the addition of halon into the premixed fuel and air causes a reduction in the laminar flame speed and a subsequent increase in the effective time lag between velocity (or pressure) perturbations and periodic heat release. This time lag is then found, through one-dimensional acoustic modeling, to result in the possibility of a mode switch in the device, consistent with experimental observations.

KEYWORDS:

• Pulse Combustion
• Flame Inhibition
• Combustion Instabilities