Effect of Sound Field on a Round Air Impingement Jet

Abstract

The local heat transfer and static pressure on a heated plate is reported with an air jet produced by a circular nozzle under tone-excitation with a frequency range of f_e = 0–300 Hz. The Reynolds numbers were (1.7 – 4.2) × 10⁴, and the nozzle-to-plate spacings were L/d = 6, 8, and 10. For all spacing, the isopressure and Nusselt number contours changed a shape from a concentric circle to an elliptic or peanut shape and changed back to a concentric circle with an increase of the tone-exciting frequency. These phenomena might be attributed to the induced vorticities observed as a non circular orifice jet.

Keywords:

• impingement jet
• acoustic excitation
• heat transfer
• circular nozzle
• flow visualization