Conjugate Analysis of Two-Dimensional Ablation and Pyrolysis in Rocket Nozzles

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Show simple item record Cross, Peter 2018-01-31T18:19:20Z NO_RESTRICTION 2018-01-31T18:19:20Z 2017
dc.description.abstract The development of a methodology and computational framework for performing conjugate analyses of transient, two-dimensional ablation of pyrolyzing materials in rocket nozzle applications is presented. This new engineering methodology comprehensively incorporates fluid-thermal-chemical processes relevant to nozzles and other high temperature components, making it possible, for the first time, to rigorously capture the strong interactions and interdependencies that exist between the reacting flowfield and the ablating material. By basing thermal protection system engineering more firmly on first principles, improved analysis accuracy can be achieved. The computational framework developed in this work couples a multi-species, reacting flow solver to a two-dimensional material response solver. New capabilities are added to the flow solver in order to be able to model unique aspects of the flow through solid rocket nozzles. The material response solver is also enhanced with new features that enable full modeling of pyrolyzing, anisotropic materials with a true two-dimensional treatment of the porous flow of the pyrolysis gases. Verification and validation studies demonstrating correct implementation of these new models in the flow and material response solvers are also presented. Five different treatments of the surface energy balance at the ablating wall, with increasing levels of fidelity, are investigated. The Integrated Equilibrium Surface Chemistry (IESC) treatment computes the surface energy balance and recession rate directly from the diffusive fluxes at the ablating wall, without making transport coefficient or unity Lewis number assumptions, or requiring pre-computed surface thermochemistry tables. This method provides the highest level of fidelity, and can inherently account for the effects that recession, wall temperature, blowing, and the presence of ablation product species in the boundary layer have on the flowfield and ablation response. Multiple decoupled and conjugate ablation analysis studies for the HIPPO nozzle test case are presented. Results from decoupled simulations show sensitivity to the wall temperature profile used within the flow solver, indicating the need for conjugate analyses. Conjugate simulations show that the thermal response of the nozzle is relatively insensitive to the choice of the surface energy balance treatment. However, the surface energy balance treatment is found to strongly affect the surface recession predictions. Out of all the methods considered, the IESC treatment produces surface recession predictions with the best agreement to experimental data. These results show that the increased fidelity provided by the proposed conjugate ablation modeling methodology produces improved analysis accuracy, as desired.
dc.language.iso en_US
dc.subject Ablation
dc.subject Pyrolysis
dc.subject Rocket Nozzle
dc.subject Modeling and Simulation
dc.subject Computational Fluid Dynamics
dc.subject Computational Heat Transfer
dc.title Conjugate Analysis of Two-Dimensional Ablation and Pyrolysis in Rocket Nozzles
dc.type Thesis en_US
dc.description.thesisdegreename PHD
dc.description.thesisdegreediscipline Aerospace Engineering
dc.description.thesisdegreegrantor University of Michigan, Horace H. Rackham School of Graduate Studies
dc.contributor.committeemember Boyd, Iain D
dc.contributor.committeemember Atreya, Arvind
dc.contributor.committeemember Duraisamy, Karthik
dc.contributor.committeemember Raman, Venkatramanan
dc.subject.hlbsecondlevel Aerospace Engineering
dc.subject.hlbtoplevel Engineering
dc.identifier.orcid 0000-0003-4612-6963 Cross, Peter; 0000-0003-4612-6963 en_US
dc.owningcollname Dissertations and Theses (Ph.D. and Master's)
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