TY - GEN
T1 - Acoustic oscillations in a cylindrical chamber with a hub baffle
AU - Acker, Thomas L.
AU - Mitchell, Charles E.
AU - Cody, Jonathan D.
N1 - Publisher Copyright:
© 1999 by the American Institute of Aeronautics and Astronautics, Inc.
PY - 1999
Y1 - 1999
N2 - The combustion-driven acoustic oscillations that occur in liquid propellant rocket engines are often similar in shape and frequency to the modes of oscillation that exist in a closed cylindrical chamber. Hub baffles can be employed to remove low-order radial modes of oscillation. In order to determine the impact of a hub baffle on low-order radial oscillations in a closed, cylindrical chamber, an analytical and computer model was developed. The governing equations of motion were solved using an eigenfunction matching technique to determine the acoustic modes of oscillation in a closed cylindrical chamber configured with a hub baffle. Results from the model show that short hub baffles significantly influence low-order radial oscillations, depressing the frequency and altering the shape of the wave. As the length of the baffle is increased, however, the radial modes of oscillation combine with successively higher longitudinal modes. The implication of this result to the overall acoustic stability of a combustion chamber is that this mode-shifting behavior may inhibit a large shift in the oscillatory frequency out of the range of frequencies sensitive to the combustion process. Furthermore, multiple solutions of the wave shape and frequency are shown to exist at some baffle lengths.
AB - The combustion-driven acoustic oscillations that occur in liquid propellant rocket engines are often similar in shape and frequency to the modes of oscillation that exist in a closed cylindrical chamber. Hub baffles can be employed to remove low-order radial modes of oscillation. In order to determine the impact of a hub baffle on low-order radial oscillations in a closed, cylindrical chamber, an analytical and computer model was developed. The governing equations of motion were solved using an eigenfunction matching technique to determine the acoustic modes of oscillation in a closed cylindrical chamber configured with a hub baffle. Results from the model show that short hub baffles significantly influence low-order radial oscillations, depressing the frequency and altering the shape of the wave. As the length of the baffle is increased, however, the radial modes of oscillation combine with successively higher longitudinal modes. The implication of this result to the overall acoustic stability of a combustion chamber is that this mode-shifting behavior may inhibit a large shift in the oscillatory frequency out of the range of frequencies sensitive to the combustion process. Furthermore, multiple solutions of the wave shape and frequency are shown to exist at some baffle lengths.
UR - http://www.scopus.com/inward/record.url?scp=84982318050&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84982318050&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84982318050
SN - 9780000000002
T3 - 5th AIAA/CEAS Aeroacoustics Conference and Exhibit
SP - 1112
EP - 1122
BT - 5th AIAA/CEAS Aeroacoustics Conference and Exhibit
PB - American Institute of Aeronautics and Astronautics Inc, AIAA
T2 - Aeroacoustics Conference and Exhibit, AIAA/CEAS 1999
Y2 - 10 May 1999 through 12 May 1999
ER -