Linear stability analysis of baffled combustion chamber with radial and circumferential blades

A linear acoustic analysis has been conducted to study the combustion instability characteristics of baffled combustion chambers. The theoretical formulation is based on a generalized three-dimensional wave equation. Normal mode expansion and spatial averaging techniques are implemented to solve for the acoustic motions in the chamber. Several specific effects of baffles are presented as mechanisms by which baffles eliminated combustion instabilities. Included are longitudinalization of transverse waves inside baffle compartments, restriction of velocity fluctuations near the injector face, and decreased oscillation frequency. Potential destabilizing influences of baffles are found to be the concentration of acoustic pressure or velocity at the injector face, depending on chamber geometry and excitation modes.