An Experimental Study of Impinging Synthetic Jets for Heat Transfer Augmentation

摘要

According to recent trends in the field of miniature electronics, the need for compact cooling solutions compatible with very thin profiles and small footprint areas is inevitable. Impinging synthetic jets are recognized as a promising technique for cooling miniature surfaces like laptops, tablets, smart phones and slim TV systems. Effect of jet to cooled surface spacing is crucial in cooling performance as well as predicting Nusselt number for such spacing. An experimental study has been performed to investigate the cooling performance of two different synthetic jets actuated with piezoelectric actuators cooling over a vertical surface. Results showed that a major degradation of heat transfer when jets are close to the surface is occurred. Slot synthetic jets showed a better performance in terms of coefficient of performance (COP) than semi-confined circular jets for small jet to surface spacing. Later, a correlation is proposed for predicting Nu number for a semi-confined circular synthetic jet accounting the effects of Re number (500 ≤ Re_j ≤ 1150), jet-to-surface spacing (H/D = 2 and H/D = 4) and the stroke length (1.75 ≤ L_0/D ≤ 4.75 and L_0/H ＜ 2.5). It is found that correlation can provide predictions with an R~2 value of over 98%.