Control of chaos in combustion reactions

The chaotic evolution in the combustion of CO in a well-stirred now reactor is controlled experimentally using a modified form of the simple proportio nal feedback (SPF) algorithm. An unstable period-1 oscillation is stabilize d through the imposition of small, appropriate perturbations which are calc ulated from the observed experimental response of the system and do not req uire any information concerning the reaction mechanism. It is observed that the algorithm is significantly more efficient if these perturbations are a pplied for only a fraction of the oscillatory period. A similar observation is made from a numerical study of a model for the H-2 + O-2 reaction, and it is shown that this arises because the perturbations shift the system sig nificantly from the attractor of the unperturbed system. The duration of th e perturbation in each cycle then becomes a second control parameter and ef fects a higher-dimensional control algorithm in a simple manner appropriate to experimental implementation for such demanding systems. The control str ategy is seen to be sufficiently robust to operate even though the system s hows a marked drift over the course of the experiment. Some comments concer ning strategies for the optimal implementation of SPF methods are then made .