Robust Low-Boom Design Based on Near-Field Pressure Signature in Whole Boom Carpet

An inverse low-boom design method using a reversed equivalent area Ae,r based on off-body pressure distributions is effective because this method captures three-dimensional effects in a flowfield. In this paper, a robust low-boom design method using Ae,r is proposed to consider off-track sonic boom...

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Bibliographic Details
Published in:Journal of aircraft 2017-05, Vol.54 (3), p.918-925
Main Authors: Ueno, Atsushi, Kanamori, Masashi, Makino, Yoshikazu
Format: Article
Language:English
Subjects:
Acceptable noise levels
Algorithms
Cost analysis
Design techniques
Free form
Loudness
Multipoles
Optimization
Robust design
Sonic booms
Three dimensional flow
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Summary:An inverse low-boom design method using a reversed equivalent area Ae,r based on off-body pressure distributions is effective because this method captures three-dimensional effects in a flowfield. In this paper, a robust low-boom design method using Ae,r is proposed to consider off-track sonic boom loudness. Computing costs are reduced by applying multipole analysis, which allows the capture of three-dimensional effects, even when an off-body location is close to a body. In terms of robustness, it is difficult to set feasible target Ae,r distributions in a whole boom carpet. Unfeasible targets may lead to results contrary to the design intent. Thus, the target is imposed only on the undertrack Ae,r distribution. In addition, second derivatives of Ae,r having direct relation to the F function are controlled in the whole boom carpet. As a result, second derivatives are successfully controlled as intended by free-form deformation and genetic-algorithm-based optimization. The undertrack Ae,r meets the target with acceptable deviation as well. As compared with the undertrack low-boom design, the robust design reduces the maximum perceived level in the whole boom carpet by 1.5 dB.
ISSN:0021-8669
1533-3868
DOI:10.2514/1.C033972