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Modeling for Control Design of an Axisymmetric Scramjet Engine Isolator

Zinnecker, Alicia M.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1354215841

Abstract Details

2012, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
Renewed interest in scramjet propulsion has motivated efforts to construct models of the scramjet engine flow path that capture transient flow dynamics to an extent that allows model-based control design. In particular, a model of the propagation of the shock wave due to a change in backpressure is needed for use in designing a controller for unstart prevention. A simplified modeling process considers the engine as the cascade of an inlet/isolator subsystem and a combustor subsystem, with emphasis placed on constructing a model of the (axisymmetric) isolator. Two types of models were considered in this effort: physics-based models constructed through spatial discretization of the compressible Euler equations and data-based models constructed through system identification using computational fluid dynamics (CFD) data. While physics-based models constructed from the two-dimensional Euler equations were found to be too expensive, a reduced-order model based on the one-dimensional Euler equations was found appropriate for the task at hand. Concurrently, a set of linear isolator models were constructed through application of subspace state-space identification technique to CFD data. An unstructured representation of uncertainty in this model was constructed from covariance data. Combining these results with error and residual analysis, a single linear model was chosen for consideration in control design. Based on a mixed-sensitivity approach, an unstable and a stable controller were designed for this model with the goal of anchoring the shock wave at a specified location in the presence of an input disturbance. While both controllers were successful in maintaining the shock location within 3 cm of the expected location for the nominal model, it was found that the controller with stable dynamics resulted in enhanced robustness for the closed-loop system. The model was then validated in closed-loop with the physics-based model, where the controller successfully meets the design goal despite limitations in the nonlinear model. This shows the promise of applying reduced-order model-based control design to the problem of active unstart prevention in a scramjet engine.
Andrea Serrani (Advisor)
Jeffrey Donbar (Committee Member)
Kevin Passino (Committee Member)
Umit Ozguner (Committee Member)
300 p.
Aerospace Engineering; Electrical Engineering
scramjet engines; engine modeling; unstart; disturbance rejection control; physics-based modeling; data-based modeling

Recommended Citations

Citations

  • Zinnecker, A. M. (2012). Modeling for Control Design of an Axisymmetric Scramjet Engine Isolator [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354215841

    APA Style (7th edition)

  • Zinnecker, Alicia. Modeling for Control Design of an Axisymmetric Scramjet Engine Isolator. 2012. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1354215841.

    MLA Style (8th edition)

  • Zinnecker, Alicia. "Modeling for Control Design of an Axisymmetric Scramjet Engine Isolator." Doctoral dissertation, Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354215841

    Chicago Manual of Style (17th edition)

osu1354215841
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© 2012, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.