The unsteady flow downstream of a blade row with mean loading

In this paper we consider the interaction between vortical gusts of reduced frequency k and a cascade of flat-plate blades at an angle of inclination 5 to the oncoming subsonic mean flow. In the asymptotic limit k ≫ 1 with kδ = O(1) it turns out that the unsteady flow can be described using matched asymptotic expansions, and in an earlier paper we have described how to use this method to determine the radiation field upstream of the cascade. In this paper we turn our attention to the field between the blades and downstream of the cascade; the theoretical framework and principal analytical expressions for the field are described here, while the results of a full parametric study will be presented at a later date.