Filtering and control of flow in a model scramjet engine
- The continuous fueling of a scramjet causes a shock to develop in the isolator which will cause the engine to stall when it reaches the inlet. To prevent the engine from stalling fuel may be injected in bursts which allows the shock to weaken between each burst. The rate at which the shock grows and dissipates depends strongly on the amount of fuel injected, the geometry of the engine and the environment in which the engine is operated. In realistic operating conditions, the environment is never fully known to the operator and the amount of heat released by combustion may be more or less than intended. As a result when a deterministically stable fueling schedule is applied in the presence of stochastic perturbations to the heat release mechanism or random fluctuations in the environment the engine may stall. This thesis presents a control algorithm that prevents a model scramjet from stalling when operated for an extended period of time in an uncertain environment. A quasi one dimensional model of a scramjet engine is used to study the effect of heat release on the development and growth of a shock in the isolator. It is shown that when the engine is fueled with periodic bursts and operated under deterministic conditions there is a clear threshold between fueling parameters ranges where the flow in the engine remains stable and where the engine stalls. A novel parametrization of the uncertainty in the heat-release mechanism and inflow properties is presented; it is demonstrated that the instabilities identified in the deterministic study are amplified by the addition of stochastic perturbations and cause significant variability in the state of the engine. This uncertainty in the state of the engine motivates the use of a filtering algorithm to accurately estimate the full state of flow in the engine based on noisy observations; both the particle filter and the ensemble Kalman filter are shown to accurately track the location of the shock in the engine. Using the filtered estimate of the engine's state, a heuristic control for heat-release is developed that prevents the engine from stalling and delivers three times the thrust as the stable periodic heat-release schedule.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|West, Nicholas Jordan
|Stanford University, Institute for Computational and Mathematical Engineering.
|Glynn, Peter W
|Glynn, Peter W
|Statement of responsibility
|Nicholas J. West.
|Submitted to the Institute for Computational and Mathematical Engineering.
|Thesis (Ph.D.)--Stanford University, 2012.
- © 2012 by Nicholas Jordan West
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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