자료유형  

 학위논문

Control Number  

0017164813

International Standard Book Number  

9798346380337

Dewey Decimal Classification Number  

790

Main Entry-Personal Name  

Needels, Jacob Troy.

Publication, Distribution, etc. (Imprint  

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

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

123 p.

General Note  

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

General Note  

Advisor: Alonso, Juan.

Dissertation Note  

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

Summary, Etc.  

요약The trade between computational cost and model accuracy is a fundamental challenge in engineering design: models of higher fidelity (i.e. physical accuracy) typically require additional cost. Resource constraints fundamentally limit the amount of high-fidelity information available to engineers during design cycles, often requiring decisions to be made with incomplete information. Simply substituting in simplified, low-fidelity tools may guide the system to a non-optimal or infeasible configuration, introducing risk in the design process.The design of hypersonic glide vehicles exemplifies these challenges. The challenges involved with experimental testing place a strong reliance on numerical models for design insight, but com- putational fluid dynamics simulations of aerodynamic and aerothermal conditions, capturing all relevant physics, are computationally expensive. Furthermore, the tight coupling between trajec- tory performance and vehicle configuration necessitates analysis at a wide range of flight conditions, exacerbating computational cost by requiring a large number of simulations. This thesis examines the use of multi-fidelity modeling strategies to reduce the cost of multidisciplinary analysis and op- timization of hypersonic vehicles while retaining a level of accuracy in results consistent with the highest level of fidelity.A multi-fidelity framework for aerodynamic and aerothermal modeling of hypersonic vehicles is introduced and applied to the simulation of a hypersonic glide vehicle. An integrated, low- fidelity modeling framework for parametric geometries, SHARPE, is developed, providing comparable predictions to the SU2 computational fluid dynamics solver for hypersonic conditions, but with significantly reduced computational cost. Predictions from these tools are used to construct surrogate models using multi-fidelity Gaussian process regression. The resulting surrogate models are then used in the trajectory simulation of a notional hypersonic glide vehicle, and the impact of surrogate accuracy on trajectory performance is examined.Given the observation that realized trajectories comprise a small subset of the vehicle state space, strategies for using trajectory information to improve sampling efficiency are explored. A methodology for sampling based on sequentially refined estimates of the true trajectory is developed, and shown to reduce range prediction error relative to a uniform sampling policy. The sensitivity of trajectory quantities to aerodynamic parameters is efficiently computed using the adjoint equations of the vehicle dynamics. A sampling algorithm combining trajectory and sensitivity information is presented and applied to aerodynamic surrogate models, resulting in consistently more accurate range predictions than other policies examined.Finally, multi-fidelity aerodynamic and aerothermal surrogate models trained over a joint ve- hicle design-state-control space are integrated into a simple hypersonic glide vehicle optimization framework. Multi-fidelity predictions of range performance and thermal protection system sizing are shown to be substantially modified from low-fidelity alone predictions by employing a small amount of multi-fidelity data.

Subject Added Entry-Topical Term  

Design optimization.

Subject Added Entry-Topical Term  

Heat.

Subject Added Entry-Topical Term  

Reynolds number.

Subject Added Entry-Topical Term  

Geometry.

Subject Added Entry-Topical Term  

Normal distribution.

Subject Added Entry-Topical Term  

Altitude.

Subject Added Entry-Topical Term  

Design.

Subject Added Entry-Topical Term  

Fluid mechanics.

Added Entry-Corporate Name  

Stanford University.

Host Item Entry  

Dissertations Abstracts International. 86-05B.

Electronic Location and Access  

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Control Number  

joongbu:656211