Vortex-Driven Sound in a Cylindrical Cavity.

An experimental investigation of the flow induced acoustic response of a cylindrical cavity to variations in the stiffness of baffles that cause flow separation and vortex shedding is presented. Vortex shedding in the Space Shuttle solid rocket motors (SRMs) contributes to undesirable combustion instabilities or oscillations in the propellant burn rate that can introduce detrimental vibratory loads to the shuttle and its cargo, including astronauts who complain of a "rough ride." This study presents a cold flow simulation of the conditions that produce vortex shedding in the SRMs using a cylindrical cavity with annular protrusions or baffles extending from the cavity walls into the flow path. This work provides quantification of the frequency and relative amplitude of this flow induced acoustic response, called a hole tone response. Specifically investigated are the effects of variable baffle stiffness and of baffle resonance excitation on the acoustic frequency and amplitude of the cavity response.