Dynamic phase compensation in Modulated-Demodulated Control for Pulsed jet injection

This paper proposes the addition of dynamic phase compensation to modulated-demodulated controllers used for disturbance rejection/reference tracking and demonstrates a novel application of repetitive control for pulsed jet injection. In cases where a plant has rapidly varying phase near the frequency or frequencies to be controlled, conventional static phase compensation may be inadequate due to the propensity to create peaking in the sensitivity function. Dynamic phase compensation improves the disturbance rejection characteristics of modulated-demodulated controllers by inverting the plant phase over some frequency band in the "baseband" coordinates. Both static and dynamic phase compensation controllers are compared on an experimental apparatus that is used to study pulsed jet injection. The controllers are used to track a square wave in the temporal velocity profile of a pulsed jet of air using active forcing. In this application pulsing the jet improves the mixing and spread of the jet which are useful for energy generation and aerospace applications.