Effects of Two DOF Lining Tolerances on Modeled Inlet Acoustic Attenuation
The effect of manufacturing tolerances on realized attenuation for two degree of freedom linings is investigated with the use of lining models and finite element duct propagation codes. Acoustic linings are created for a small turbofan engine that optimizes attenuation at takeoff/sideline and approach conditions. Lining physical and geometric parameters are set which best meet the optimum impedance requirements at two target frequencies. Variations of these parameters representing realistic manufacturing tolerances are used to systematically examine the effect on installed impedance and predicted attenuation. Attenuation at sideline and approach conditions is found to sensitive to manufacturing tolerances around optimum conditions. It is found that local lining impedance variation due to local Sound Pressure Level also has a significant effect on realized attenuation in the sideline case. The results of the study are case dependent; however the analysis scheme presented provides a method for cost-benefit analysis of maintaining tight tolerances on manufacturing processes.
D. R. Burd et al., "Effects of Two DOF Lining Tolerances on Modeled Inlet Acoustic Attenuation," 15th AIAA/CEAS Aeroacoustics Conference, American Institute of Aeronautics and Astronautics (AIAA), May 2009.
Mechanical and Aerospace Engineering
Keywords and Phrases
Acoustic Linings; Freedom Linings; Lining Models; Manufacturing Tolerances
Article - Conference proceedings
© 2009 American Institute of Aeronautics and Astronautics (AIAA), All rights reserved.