Strategies for active flow control of high-speed jets

Abstract

The global challenges of improving performance, reducing wastage, and minimizing environmental impact for all flow systems require understanding and active control. The particular application chosen here is a high-speed turbulent jet controlled for either noise mitigation or mixing enhancement. Plasma actuators had previously demonstrated promise in achieving these goals in an open-loop control configuration. This talk will mainly focus on two strategies for active flow control. The first is a simple and robust technique called extremum-seeking control that doesn't require any model. However, for the same reason, it has a slow response speed. The second is a reduced-order modeling approach geared towards conventional model-based feedback control – it is designed to have a faster response. The model is developed using a combination of detailed experimentation and theoretical analysis, and it reproduces the overall effects of such actuation on the jet. The three main ingredients of the model are stochastic estimation, proper orthogonal decomposition, and Galerkin projection. Extensions of both the approaches to other flows are discussed.