Effects of the synthetic jet on the flow field and heat transfer over a surface-mounted square rib

Abstract

In this article, a synthetic jet manipulates the flow behavior behind the surface-mounted square rib for heat transfer enhancement. Effects of operating frequencies and amplitudes on the near wake flow field of the rib are studied. Experiments are performed at Re=32000 (based on the Hydraulic diameter of the rectangular test section) with the Synthetic jet flush mounted at the bottom of the test section. Particle Image Velocimeter (PIV) captures a plane's instantaneous and time-averaged spatial flow information. The hotwire anemometer in CTA mode is used for temporal information of the flow field. The effect of synthetic jet on heat transfer downstream of the square rib is measured using Liquid crystal thermography(LCT). The result includes time-averaged velocity magnitude, vorticity, streamlines, turbulence quantities such as turbulence intensity, Reynolds stress, and rms velocities. The concise study indicates that a drastic reduction of reattachment length occurs at frequencies and amplitude of the synthetic jet. The study's unique contribution is the complete removal of the recirculation bubble by using the synthetic jet at a particular upstream position(X/D=-1). At 50 Hz frequency, the maximum heat transfer rate is obtained.