Simultaneous Flowfield and Surface-Deflection Measurements of an Axisymmetric Jet and Adjacent Surface

Abstract

The interaction of an underexpanded jet and a nearby adjacent compliant surface is considered in an effort to gain insight into the relevant fluid–structure interaction. High-quality simultaneous flowfield and surface-deflection data were obtained in this high-Reynolds-number flow using nonintrusive, full-field, optical diagnostics (planar particle image velocimetry and stereo/three-dimensional digital image correlation, respectively). Both experimental setups were rigorously validated in terms of their measurement resolution and accuracy, both individually and in a combined manner. The full-field surface deflection data indicate that the surface has a predominantly quasi-static response characterized by a “standing-wave” type contour along the jet axis. A large jetward deflection, on the order of 10 plate thicknesses, was observed near the first shock-cell region, which is consistent with previously obtained rigid-surface case surface pressure measurements. The compliant-surface flowfield was analyzed and compared to the rigid-surface case results in key regions: the initial expansion region, through the shock/boundary-layer interaction, the shock/boundary-layer interaction separation region, the shock-cell structure of the remainder of the jet plume, the near-wall boundary layer, and the far-field conditions. Notable differences were observed before, within, and after the shock/boundary-layer interaction region as well as within the boundary layer and in the shock-cell structure.