TY - GEN
T1 - Evaluation of actuator disk theory for predicting indirect combustion noise
AU - Mishra, Ashish
AU - Bodony, Daniel J.
N1 - Funding Information:
This work was supported by NASA , through the subsonic fixed wing NRA program. Dr. Lennart Hultgren was the technical monitor.
PY - 2012
Y1 - 2012
N2 - Indirect combustion noise is believed to be a key component of turbofan engine core noise, but existing experimental data have not been able to definitively determine its importance. Instead, actuator disk theory (ADT) as developed by Cumpsty & Marble (Proceedings of the Royal Society of London A, 357, pp. 323-344, 1977), is commonly used to estimate its contribution based on combustor exit conditions and changes in the mean flow across blade rows. The theory, which assumes planar propagation of acoustic, entropic, and vortical waves in the long wavelength limit, is assessed by comparing its predictions to those from two-dimensional compressible Euler calculations of idealized entropy disturbances interacting with a 1980s era NASA turbine stator. Both low-frequency planar waves of constant frequency and higher-frequency, localized entropy disturbances are considered, with the former being within ADT's range of applicability and the latter outside of it. It is found that ADT performs well for the cut-on acoustic modes generated by the entropy-blade interaction but it's accuracy suffers for the cut-off acoustic modes, which could impact indirect combustion noise predictions for turbines with closely spaced blade rows.
AB - Indirect combustion noise is believed to be a key component of turbofan engine core noise, but existing experimental data have not been able to definitively determine its importance. Instead, actuator disk theory (ADT) as developed by Cumpsty & Marble (Proceedings of the Royal Society of London A, 357, pp. 323-344, 1977), is commonly used to estimate its contribution based on combustor exit conditions and changes in the mean flow across blade rows. The theory, which assumes planar propagation of acoustic, entropic, and vortical waves in the long wavelength limit, is assessed by comparing its predictions to those from two-dimensional compressible Euler calculations of idealized entropy disturbances interacting with a 1980s era NASA turbine stator. Both low-frequency planar waves of constant frequency and higher-frequency, localized entropy disturbances are considered, with the former being within ADT's range of applicability and the latter outside of it. It is found that ADT performs well for the cut-on acoustic modes generated by the entropy-blade interaction but it's accuracy suffers for the cut-off acoustic modes, which could impact indirect combustion noise predictions for turbines with closely spaced blade rows.
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U2 - 10.2514/6.2012-2086
DO - 10.2514/6.2012-2086
M3 - Conference contribution
AN - SCOPUS:85087594281
SN - 9781600869327
T3 - 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)
BT - 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)
PB - American Institute of Aeronautics and Astronautics Inc.
T2 - 18th AIAA/CEAS Aeroacoustics Conference 2012 (33rd AIAA Aeroacoustics Conference)
Y2 - 4 June 2012 through 6 June 2012
ER -