Professor F. E. C. Culick
        California Institute of Technology

     MC 205-45, Pasadena, CA 91125
   Tel: 626.395.4783
  Fax: 626.395.8469

Return Home research

nonlinear acoustics in combustion systems

This is a general program of analysis and numerical computations concerned with the transient nonlinear behavior of unsteady motions in combustion chambers. The chief theoretical problems are the nonlinear instability and limit cycles of motions caused by energy release in a confined volume. Topics of current interest are the excitation of nonlinear waves by randomly varying sources, such as turbulent flames and flow fluctuations; excitation of large amplitude motions by combustion in vortices; and the general theory for nonlinear behavior of dynamical systems having many degrees of freedom.

active & passive control of combustion systems
Part of a program of research devoted to the application of modern control theory and methods to controlling unsteady motions in combustion chambers, this subject falls broadly in the area of control of distributed systems. Four features that distinguish the general problem of controlling a combustion system from controlling more familiar electromechanical systems are the presence of a noise intrinsic to the system; combustion systems always contain time delays that cannot be ignored; reacting flows are intrinsically nonlinear, and the property that controlling a combustion system usually causes significant changes in the parameters characterizing the system. Theoretical work encompasses both controls issues and the analysis of an unsteady reacting flow represented as a synthesis of nonlinear acoustic modes. The results are useful in conducting controlled laboratory experiments and ultimately as means for controlling oscillations commonly encountered in full-scale liquid-fueled propulsion systems. See the RTO publication Unsteady Motions in Propulsion Systems, to be published by Cambridge University Press.