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A Discrete Adjoint Framework for Turbulent Hypersonic Flows in Thermochemical Nonequilibrium.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	A Discrete Adjoint Framework for Turbulent Hypersonic Flows in Thermochemical Nonequilibrium./
Author:	Maier, Walter Thomas.
Description:	1 online resource (166 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 84-12, Section: B.
Contained By:	Dissertations Abstracts International84-12B.
Subject:	Energy. -
Online resource:	click for full text (PQDT)
ISBN:	9798379651480

A Discrete Adjoint Framework for Turbulent Hypersonic Flows in Thermochemical Nonequilibrium.
Maier, Walter Thomas.

A Discrete Adjoint Framework for Turbulent Hypersonic Flows in Thermochemical Nonequilibrium. - 1 online resource (166 pages)

Source: Dissertations Abstracts International, Volume: 84-12, Section: B.

Thesis (Ph.D.)--Stanford University, 2023.

Includes bibliographical references

Hypersonic vehicle design and analysis continues to challenge the aerospace community. These systems operate in a unique flow environment characterized by thermochemical nonequilibrium effects, adding constraints and complexity not observed in other flow regimes. Experimental testing of hypersonic vehicles is difficult and prohibitively costly, prompting a reliance on numerical simulations in the design process. These simulations must resolve the high-temperature, atomic-scale physical phenomena to accurately predict vehicle performance parameters such as lift, drag, control authority, and surface heat transfer. Subsequently, additional physical models are added to the highfidelity computational fluid dynamics (CFD) suites, increasing the simulation cost exponentially. As a result, CFD is substituted with low-fidelity correlation-based models for repetitive gradient computations. This yields, at best conservative vehicle configurations and, at worst, failed designs. Consequently, despite the rapid growth of computational power, hypersonic vehicle design has stagnated without the proper methods to efficiently incorporate CFD into the design process. This work explores the use of the discrete adjoint methodology to reintegrate high-fidelity simulations into the preliminary design phases for hypersonic vehicle systems.This dissertation presents, to the author's knowledge, the first discrete adjoint framework for the efficient computation of aerothermodynamic sensitivities of turbulent hypersonic flows in thermochemical nonequilibrium. The dissertation first highlights the creation, verification, and validation of a finite-volume-method (FVM) hypersonic flow simulation suite, which includes the necessary chemical, thermodynamic, turbulence, and boundary condition models. The discrete adjoint method for these additional models is then verified by comparing the computed gradients of both pressureand thermal-based objectives against those calculated using the finite difference method. The discrete adjoint framework is proven advantageous in dimensionality and computational cost, showing a five-fold improvement in simulation time in these small studies. Substantial computational cost savings are expected as the discrete adjoint technique is applied to complete higher-dimensional design studies.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798379651480Subjects--Topical Terms:

784773
Energy.
Index Terms--Genre/Form:

554714
Electronic books.

A Discrete Adjoint Framework for Turbulent Hypersonic Flows in Thermochemical Nonequilibrium.
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520 $a Hypersonic vehicle design and analysis continues to challenge the aerospace community. These systems operate in a unique flow environment characterized by thermochemical nonequilibrium effects, adding constraints and complexity not observed in other flow regimes. Experimental testing of hypersonic vehicles is difficult and prohibitively costly, prompting a reliance on numerical simulations in the design process. These simulations must resolve the high-temperature, atomic-scale physical phenomena to accurately predict vehicle performance parameters such as lift, drag, control authority, and surface heat transfer. Subsequently, additional physical models are added to the highfidelity computational fluid dynamics (CFD) suites, increasing the simulation cost exponentially. As a result, CFD is substituted with low-fidelity correlation-based models for repetitive gradient computations. This yields, at best conservative vehicle configurations and, at worst, failed designs. Consequently, despite the rapid growth of computational power, hypersonic vehicle design has stagnated without the proper methods to efficiently incorporate CFD into the design process. This work explores the use of the discrete adjoint methodology to reintegrate high-fidelity simulations into the preliminary design phases for hypersonic vehicle systems.This dissertation presents, to the author's knowledge, the first discrete adjoint framework for the efficient computation of aerothermodynamic sensitivities of turbulent hypersonic flows in thermochemical nonequilibrium. The dissertation first highlights the creation, verification, and validation of a finite-volume-method (FVM) hypersonic flow simulation suite, which includes the necessary chemical, thermodynamic, turbulence, and boundary condition models. The discrete adjoint method for these additional models is then verified by comparing the computed gradients of both pressureand thermal-based objectives against those calculated using the finite difference method. The discrete adjoint framework is proven advantageous in dimensionality and computational cost, showing a five-fold improvement in simulation time in these small studies. Substantial computational cost savings are expected as the discrete adjoint technique is applied to complete higher-dimensional design studies.
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