Adaptive Active Control of Instabilities

This article reports the results of an experimental investigation in which adaptive methods are applied to various situations of active control of flow instabilities: combustion instabilities, flow-excited cavity oscillations, and compressor surge. The pres ent work draws attention especially to the adaptive controller behaviour and capacities. The main results are as follows: 1) The adaptive controller manages to automatically find its optimal characteristics in order to cancel the instability in the three experiments under consideration; 2) It is able to cope with time-dependent changes in the operating condi tions such as flow velocity sweeps for the oscillating cavity and air and propane mass flow rate variations in the combustion instability experiment; and 3) In the case of the Helmholtz cavity resonator, the algorithm has also exhibited capacity to recover effective control even when initially set such that artificial closed-loop instabilities induced by the control system occurred.