ISR research accomplishments

Nonlinear Active Control of Jet Engine Stall

Research team

Eyad Abed (ECE/ISR)
Der-Cherng Liaw, Ph.D., UMCP (now at NCTU, Taiwan)
Raymond A. Adomaitis (ChE/ISR)

Accomplishment

Active control laws were designed for stabilizing jet engine stall, by applying bifurcation control to nonlinear models of axial flow compressors. The controllers employ one dimensional actuation in the form of throttle feedback.

The drive toward lighter jet engines is motivating studies into operability of the engine’s axial flow compressor close to its maximum pressure rise. The compressor is only marginally stable in this condition, and can stall under small or moderate flow disturbances.

• Active control as a means for enlarging the operating envelope of military jet engines contributes greatly to the goal of lighter weight engines.
• Active control may also help to reduce the incidence of engine stall in commercial aircraft, especially during take-off and landing.
• The project has shown the superiority of nonlinear bifurcation-theory based methods for design of simple one-dimensional throttle controllers.
• The controls allow operation up to and past the stall stability limit (“stall line” in schematic)
• The control designs have been been expanded on and implemented at the United Technologies Research Center, the Georgia Institute of Technology and at the California Institute of Technology
• Other areas in which a nonlinear performance vs. stability trade-off appears might benefit from the lessons learned in the jet engine stall application.
  

For more information

D.-C. Liaw and E. H. Abed, Active control of compressor stall inception: A bifurcation-theoretic approach, Automatica, Vol. 32, No. 1, pp. 109-115, January 1996.

AFOSR Research Highlights, March 1995

R. M. Murray, Plenary lecture, Amer. Control Conf., June 1999

ISR Technical Reports | 91-32 | 92-73 | 91-33 | 92-78 | 92-73 | 90-63 |