Adjoint-based control of afterbody flow unsteadiness in the compressible regime

Abstract

The theoretical study of a compressible afterbody flow in the subsonic regime is presented. It relies on sensitivity analyses developed in the framework of the linear global stability theory and aims at predicting beforehand the effect of a steady bulk and wall forcing on the growth rate of linear global modes. Such an analysis stands as a step in the perspective of a full control of afterbody flow unsteadiness. The sensitivity functions are derived analytically using adjoint methods and presented for the global mode responsible for the onset of a periodic regime. Various control methods are investigated, including an additional control device in the lee of the main body, heat sources, and boundary forcing. The obtained results show that the global mode is sensitive to momentum forcing along the separation line, to a localized heating in the core of the recirculating bubble, and to a blowing velocity close to the edge of the base.