Thermoacoustic Suppression in a Rotating Detonation Combustion using Perforated Liner

A perforated liner is introduced to an annular Rotating Detonation Combustor (RDC) as a means to suppress thermoacoustic modes. Perforated liners have been used historically in combustion applications as a tool to suppress acoustic coupling between the combustion products and the mixing reactants; however, their applications in RDC environments have not been explored extensively. The performance of this particular geometry is assessed through comparative analysis of pressure frequency at the exit plane of the combustor in conjunction with Spectral Proper Orthogonal Decomposition (SPOD) of high-speed, broadband imaging. The dominant detonative mode and weaker thermoacoustic modes are first identified through Fourier analysis of pressure signals at two locations azimuthally about the exit plane of the combustor. Then, using SPOD analysis of high-speed video, these modes are verified to be the result of physical instabilities occurring within the combustion process. The change in the strength of these modes is compared between the baseline combustor and the combustor with a perforated liner. Results indicate that unstable modes observed for specific operating conditions are reliably suppressed when a perforated liner is introduced. This same liner is then implemented in a centerbodiless RDC of similar geometry. In this configuration, the liner is found to completely suppress all detonative modes that are typically observed with a solid wall.