On a Radial Wall Jet Formed by a Normally-Impinging Round Synthetic Jet

Abstract

The ow eld of a radial wall jet created by the impingement of a round synthetic jet, normal to a at surface is studied in this paper. The ensuing radial wall jet is characterized using hot-wire anemometry. The wall jet is observed to exhibit self-similar behavior as distinguished by the collapse of the outer mean velocity proles, when the radial velocity, and axial coordinate are scaled by the maximum velocity (um), and outer layer half width (z1=2) respectively. While recognizing the lack of a single velocity and length scale across both the inner and outer layers, it is proposed that radial wall jets due to synthetic jet impingement, may be modeled using similarity analysis, just as radial wall jets caused by continuous jet impingement are. The dierence being, the adjustment of a single empirically determined parameter, that is reective of the enhanced momentum transfer capacity of a synthetic jet. The growth rate of the outer layer is observed to be linear, with the maximum velocity decaying as x 1 . An increase in driving amplitude (Vd) which translates into a simultaneous increase in both the stroke ratio (L=d), and Reynolds number (ReUo) associated with the synthetic jet actuator, results in an increase in the spreading rate, and decrease in the velocity decay rate of the wall jet.