Abstract
Acoustic behavior in baffled combustion chambers is numerically investigated by adopting linear acoustic analysis. Partial blade baffle, which is a variant of blade baffle, and hub-blade baffle with six blades are employed as baffle models. Through modal analysis, natural frequencies of each acoustic mode in baffled chambers are calculated and the reduction in natural frequencies caused by baffle installation is examined. Through harmonic analysis, acoustic pressure responses of each chamber to acoustic oscillating excitation are shown. The first tangential mode is found to be most sensitive to acoustic oscillation. Acoustic damping effect of baffle is quantified by damping factor. Damping effect of hub-blade baffle is the most appreciable and damping factor of partial blade baffle is much lower than that of blade baffle. Damping effect of six-blade baflle on the second tangential mode is as much as on the first tangential mode and hub-blade baffle can damp out appreciably the first tangential as well as the first radial mode with the aid of hub.