Impact of Sweeping Jet on Area-Averaged Impingement Heat Transfer

Abstract

A series of sweeping jet-impingement experiments are conducted over a circular heated surface, with a main objective of understanding the impact of the unique flow field on the resulting heat transfer. The sweeping motion of the fluidic oscillator is influenced by the sweeping frequency and sweeping angle where each is directly dependent on the geometric design (i.e. internal feedback loops, mixing chamber, etc.). The target surface consists of a heated copper disk, where heater power is supplied to the bottom surface of the disk and adjusted until a differential of 30°C is obtained between the jet and target surface temperatures. An energy balance over the target surface temperatures provides a means for calculating area-averaged heat transfer rate, hence Nusselt number. An increase in the sweeping jet’s thermal inertia initiates an augmentation in heat transfer due to sweeping motion of the jet across the target surface. PIV data was acquired for two jet configurations, confined and unconfined, so that the recirculation behavior can be determined. The fluidic oscillator is found to improve only at a low z/d. At large z/d (greater than 4 in this study), the fluidic oscillator adversely affects the heat transfer.

Numerical Simulation on Internal Flow and Heat Transfer of Sweeping Jet and Film Composite Cooling on a Flat Plate

“…Moreover, it is consistent with experimental results of Agricola (2017), Park (2018 and Zhou (2019). In addition, experimental results of Osorio (2019) showed that stagnation zone disappeared when normalized injection distance was 2, and the cooling effectiveness was the best when normalized injection distance was 3. Kim (2019) found that the overall cooling effectiveness of fluidic oscillator was higher than normal jet when normalized injection distance was less than 5.…”