자료유형  

 학위논문

Control Number  

0017164845

International Standard Book Number  

9798346394815

Dewey Decimal Classification Number  

790

Main Entry-Personal Name  

Shanbhag, Tejal Kishore.

Publication, Distribution, etc. (Imprint  

[S.l.] : Stanford University., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

140 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-05, Section: A.

General Note  

Advisor: Alonso, Juan.

Dissertation Note  

Thesis (Ph.D.)--Stanford University, 2024.

Summary, Etc.  

요약The current projection for high yearly growth in air traffic and the simultaneous rapid expansion of urban populations have created a demand for a significant reduction in aircraft noise. Jet noise is one of the most significant components of aircraft noise overall, particularly at the take-off condition. However, calculating this noise component presents a considerable technical challenge, as turbulent sound generation comprises a number of complex, interconnected physical mechanisms. Existing approaches to numerical noise prediction vary widely in cost and fidelity, spanning from empirical database interpolation to expensive LES or DNS calculations. In the context of design optimization, where repeated evaluations of a flow field are required, it is highly desirable to develop a method that minimizes computational time and expense while retaining sufficient accuracy. Hybrid methodologies based on steady RANS simulations of the jet flow are widely recognized as a well-suited alternative for this purpose. These methods post-process mean flow quantities available from RANS calculations to construct an approximate model of the jet's equivalent acoustic field.In this work, we present a study of hybrid computational aeroacoustic methods applied to computing the noise generated by subsonic and transonic free jets. The research focuses on three areas within this field. The first area is low-frequency global source modeling. We propose a wavepacket-based line source reconstruction method, using eddy viscosity augmented resolvent analysis and an explicit model of coherence decay effects. We demonstrate that this approach can accurately compute the acoustic directivity field of round jets at low frequencies. The second area is fine-scale distributed source modeling. We leverage available LES data to compute the turbulent correlation functions typically appearing in acoustic analogy source terms and investigate the validity of RANS-derived characteristic turbulent scales at different points in the flow field. We propose modifications to the standard model of turbulent scales and demonstrate the improvement in far-field SPL accuracy computed using these changes. The third area is adjoint-based nozzle geometry optimization, based on a geometric method for far-field propagation. We implement a modular acoustic prediction tool with the JAX library to enable GPU acceleration, greatly surpassing the computational performance of existing CPU-based tools. Using the associated automatic differentiation capabilities to couple with SU2's discrete adjoint solver, we perform constrained shape optimization of two nozzle geometries to minimize far-field noise.

Subject Added Entry-Topical Term  

Design optimization.

Subject Added Entry-Topical Term  

Energy.

Subject Added Entry-Topical Term  

Viscosity.

Subject Added Entry-Topical Term  

Acoustics.

Subject Added Entry-Topical Term  

Nozzle geometry.

Subject Added Entry-Topical Term  

Design.

Added Entry-Corporate Name  

Stanford University.

Host Item Entry  

Dissertations Abstracts International. 86-05A.

Electronic Location and Access  

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Control Number  

joongbu:656009