On Instability Analysis of Realistic Intake Flows

Instability analyses of incompressible ow through two intakes, both having realistic cross-sectional profiles have been performed. Without reference to concrete applications, representative duct geometries, inspired from motor racing and fighter jets has been selected. The projections on the plane normal to the streamwise ow direction normal to the plane of the intake, of two such duct geometries are depicted in figure 1; the parametric definition of these ducts is detailed in what follows. In order for the analysis to proceed two key assumptions are made. First, ow is taken to be homogeneous along the streamwise spatial direction; in section IV a suggestion is put forward on how this approximation may be relaxed. Second, ow is taken to be laminar and incompressible, driven by a constant pressure gradient along the streamwise spatial direction; section IV also discusses potential extensions of the present analysis toward compressible and turbulent ows