Knoop, P. and Culick, F. E. C. and Zukoski, E. E. (1997) Extension of the Stability of Motions in a Combustion Chamber by Nonlinear Active Control Based on Hysteresis. Combustion Science and Technology, 123 (1-6). pp. 363-376. ISSN 0010-2202 http://resolver.caltech.edu/CaltechAUTHORS:20101119-150022314
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Experimental results for instabilities in dump combustors have long shown the presence of some sort of hysteresis, in the vicinity of the stability boundary defined by flow speed and mixture ratio. This note reports measurements of the precise character of hysteresis loops found when the mixture ratio is varied with flow speed held constant. The upper branch represents relatively high amplitude limit cycles and the lower branch contains low level oscillations possibly driven by stochastic sources within the chamber. Existence of the hysteresis loops suggests the possibility of causing a transition from the upper unstable branch to the lower stable branch. This has been accomplished by injecting short pulses of secondary fuel either in the boundary layer upstream of the dump plane or in the recirculation zone. Only a single pulse is required if its flow rate and width are suitably chosen. These results demonstrate the feasibility of a novel method of active control of combustion instabilities if hysteresis is present, apparently the first example of true nonlinear control of combustor dynamics. The main advantage is the small amount of secondary fuel required. More generally, this work illustrates the value, for active control, of understanding the dynamics of the uncontrolled system.
|Additional Information:||© 1997 OPA (Overseas Publishers Association) Amsterdam B.V. Received 23 April 1996; In final form 24 September 1996. Reprints available directly from the publisher. Photocopying permitted by license only. This work was supported in part by the California Institute of Technology; partly by ENEL (Dr. Giancarlo Benelli, Program Manager); partly by the Air Force Office of Scientific Research, AFOSR Contract No. F49620-95-1-0272 (Dr. Mitat Birkan, Program Manager); and partly by the Department of Energy Grant DE-FC21-92MC2906 (Dr. Daniel Fant, Program Manager). The authors have benefited from conversations with Professor Richard Murray and also thank Sudipto Sur, Windsor Lin and Giorgio Isella for their help in carrying out some of the experimental work.|
|Group:||Guggenheim Jet Propulsion Center|
|Subject Keywords:||Hysteresis; combustion instability|
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|Official Citation:||Extension of the Stability of Motions in a Combustion Chamber by Nonlinear Active Control Based on Hysteresis P. Knoop; F. E. C. Culick; E. E. Zukoski Pages 363 – 376|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||03 Dec 2010 16:37|
|Last Modified:||26 Dec 2012 12:40|
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