Computational study of flow and thermal behavior of a single-cavity and multiple-orifice impinging synthetic jets under low orifice-to-target distances

Abstract

A computational study has been done by using circular, square and rectangular orifice shapes to explore the flow field and heat transfer characteristics of multiple synthetic jet impingement under orifice-to-plate distances of H/D = 0.10–1.00 and pitch diameter ratio of Do/D = 1.25–1.75. The multiple synthetic jet impingement has been created by using a single cavity. The validation study with an experimental study from the literature showed a good agreement. The flow characteristics have been presented as velocity contours and streamlines. By using the findings of the study correlations have been proposed to show the variation of Nuavg for various orifice geometries. The reduction in the orifice to plate distance (H/D) and raise in the pitch diameter ratio (Do/D) indicated thermally more uniform distributions. The highest Nuavg values were obtained in the limits of 0.10 ≤ H/D ≤ 0.25 for rectangular orifices, whereas for 0.50 ≥ H/D the highest Nuavg values have been obtained for circular orifices. Also, a comparison with a single orifice with the same exit area with the multiple orifice cases has been investigated, and it was observed that with the use of multiple orifices, especially at lower H/D values higher heat transfer could be obtained.