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You searched for id:"oai:etd.ohiolink.edu:osu1554740828968894". One record found.

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1. Riley, Logan Patrick. Unstart Phenomenology of a Dual-Mode Scramjet Subject to Time-Varying Fuel Input.

Degree: PhD, Aeronautical and Astronautical Engineering, 2019, The Ohio State University

Scramjet-based, air-breathing propulsion systems are poised to enable development of hypersonic defense, high speed transport, and access-to-space aerospace vehicles. A particular variant of scramjet engine, the dual-mode scramjet, is capable of operating in subsonic- and supersonic-burning modes and is attractive for flight at or above Mach 5. Despite the relative geometric simplicity of such scramjet engines, the intense hypersonic flight environment presents challenges to routine, long-duration hypersonic flight in the form of shock-turbulence interactions, heat-transfer, and turbulent-combustion.A critical component of dual-mode scramjets, the isolator, conditions the flow before it reaches the combustion zone and contains the Pre-Combustion Shock-Train (PCST) which forms in response to the pressure rise due to chemical heat release. When subjected to sufficiently large mechanically- or chemically-induced back-pressures, the isolator may unstart, resulting in the rapid ejection of the shock-train from the isolator, adversely affecting controllability and survivability of high-speed air-breathing vehicles.To better anticipate and control for isolator unstart events, detailed understanding of the combustor dynamics is required. In particular, the selection and placement of measurement sensors for ground and flight experiments is predicated on quantifying the dynamic response of the scramjet engine system. This dissertation computationally studies the isolator dynamics during a fuel-staging-induced unstart event. In this process, fuel flow rates are varied in time between two reference fueling states studied experimentally and characterized as aft-fueled and forward-fueled biased, respectively.The dynamics of a rectangular cross-section scramjet combustor, in the presence of simulated inflow-distortion, are described and quantified with respect to combustion-induced unstart. Because of the high Reynolds number and multi-physics effects of mixing and combustion, a model-based, Unsteady Reynolds-Averaged Navier-Stokes (URANS) approach is employed to study the turbulent reacting flowfield. Before characterizing unstart phenomenology, solution sensitivities to model parameters and assumptions are quantified. The primary analysis considers the dynamics of the PCST during the imposed fuel-staging transient. A wall-pressure-based shock sensor employed in experiments is used to track the response of the PCST to the heat release-induced back-pressure gradients. From this sensor, an incipient unstart condition is identified which delineates between slowly-varying, pre-unstart PCST motion and more rapid PCST unstart motion. Extending this one-dimensional sensor to the predicted two-dimensional wall field reveals strong spanwise gradients associated with side wall separation.Rectangular combustors are particularly sensitive to corner flow, including shock-induced separation and secondary flow. Commensurately, side wall separation is identified as a principal component of the unstart dynamics in this rectangular combustor.… Advisors/Committee Members: Gaitonde, Datta (Advisor).

Subjects/Keywords: Aerospace Engineering; scramjet; URANS; hypersonic; unstart; ethylene; SBLI; isolator; POD; DMD

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APA (6th Edition):

Riley, L. P. (2019). Unstart Phenomenology of a Dual-Mode Scramjet Subject to Time-Varying Fuel Input. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1554740828968894

Chicago Manual of Style (16th Edition):

Riley, Logan Patrick. “Unstart Phenomenology of a Dual-Mode Scramjet Subject to Time-Varying Fuel Input.” 2019. Doctoral Dissertation, The Ohio State University. Accessed July 20, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554740828968894.

MLA Handbook (7th Edition):

Riley, Logan Patrick. “Unstart Phenomenology of a Dual-Mode Scramjet Subject to Time-Varying Fuel Input.” 2019. Web. 20 Jul 2019.

Vancouver:

Riley LP. Unstart Phenomenology of a Dual-Mode Scramjet Subject to Time-Varying Fuel Input. [Internet] [Doctoral dissertation]. The Ohio State University; 2019. [cited 2019 Jul 20]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1554740828968894.

Council of Science Editors:

Riley LP. Unstart Phenomenology of a Dual-Mode Scramjet Subject to Time-Varying Fuel Input. [Doctoral Dissertation]. The Ohio State University; 2019. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1554740828968894

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