Toward Simple Boundary Condition Representations of Zero-Net Mass-Flux Actuators in Grazing Flow

Abstract

The paper explores a set of simple boundary conditions that can represent the flow emanating from zero-net mass-flux (ZNMF) jets in grazing flow. Results from numerical simulations of ZNMF jets in grazing flows are used to determine the key characteristics of the jet profile, and these are used to construct a series of boundary condition models. These various boundary conditions are then tested for a jet exhausting in an attached boundary layer as well as a boundary layer with an induced separation bubble.

On synthetic jet actuation for aerodynamic load control

“…Furthermore, the behavior in time cannot be approximated accurately by a sine function. Also, the non-uniform velocity distributions given by equation 3.145, which were proposed by Aram et al [96] and consist of three piecewise linear parts across the slit with a sinusoidal behavior in time, are unable to accurately represent the normal velocity profiles observed in figure 6.32. Including the slit and at least some part of the cavity below the slit in the computational domain is therefore necessary to let the synthetic jet adapt to the cross-flow along the surface of the airfoil.…”

“…During the ingestion phase, the tangential velocity components cannot be prescribed, they follow from the solution in the computational domain. -For the case of a slit, Aram et al [96] construct a series of simplified, twodimensional velocity boundary conditions. The jet-exit-width w is divided into three parts by introducing four points, x 1... 4 , where x 1 and x 4 are located at the edges (where the relative velocity is always zero due to the no-slip condition), x 2 is located at 25% and x 3 is located at 75% of the jet width, see figure 3.1.…”