Analysis of Self-Excited Combustion Instabilities Using Decomposition Techniques
Technical paper Nov 2012-Jan 2013
DIRECTORATE OF ROCKET PROPULSION EDWARDS AFB CA
Pagination or Media Count:
Proper orthogonal decomposition POD and dynamic mode decomposition DMD are compared with traditional band-pass filtering based analysis for the study of self-excited combustion instabilities in a longitudinal mode rocket combustor. The POD analysis approximates the complex high-rank dynamics with simple lower-rank expressions for the mode shapes. Each POD mode, however, is comprised of multiple acoustic frequencies and specific modes of the pressure and heat release are not related, which makes the analysis more qualitative. On the other hand, the DMD analysis generates a global frequency spectrum and each mode corresponds to a specific discrete frequency. The DMD result therefore provide a quantitative means for understanding the relationship between the pressure modes and the heat release modes and for establishing the driving mechanisms responsible for the incidence of combustion instabilities. The paper uses these analyses to describe the Rayleigh index on a modal basis to shed light on the frequency-based response of the combustor flowfield.
- Physical Chemistry
- Fluid Mechanics
- Combustion and Ignition