Flow pulsation in the near-wall layer of impinging jets

Abstract

Abstract. Pulsation of impinging jets promises to become a useful way towards achieving the highest possible rate of passive scalar convective transport between fluid and a wall. Author investigated experimentally steady and pulsated impingement by hot-wire anemometer traversing along a radial line at a small height above the impingement wall. The data have shown two conspicuous local maxima of fluctuation intensity. In an attempt to reach understanding of these phenomena, numerical flowfield computations were also made, fitted to the experimental conditions. Despite simplification (isotropic handling of unsteadiness, eddies computed as Reynolds-type phase averages) the synergetic approach (experiment & computation) revealed interesting correlation and resulted in useful interpretations of the old problem of the off-axis extremes -and also brings new views on their behaviour in the pulsating jet case.

Flow "reflexion" and " refraction" on perforated wall

“…The impact distance from the nozzle exit to this plane was 13.33 b -a rather large distance for the impact (note that e.g. with the round impinging jets discussed in [10] the distances were only 3.5). The available free channel width between the elements was 0.93 b.…”