Particle image velocimetry study on dual cooling jet flows

With the advance of the Internet of Things (IoT), electronics are becoming more prevalent in applications outside the traditional consumer electronics environment. Current electronic systems are often challenged by operation at extreme low temperature, high temperature, rapid cycling temperature, vibration, or dust-filled environments. Typical systems for these environments are natural convection cooled and sealed to protect the interior electronics from the exterior environment but this has as consequence that efficient heat removal is challenging, limiting electronics capability. Application of fans is often considered to negatively impact reliability. Dual Cool Jet (DCJ) is a variant of variable orifice synthetic jet(VO-SJ) consisting of piezo actuated metal disks that are mechanically configured to form a miniature thin form factor air mover. The DCJ does not require bearings or a DC motor making the air mover potentially lower cost and more reliable, making it an attractive candidate for electronics in harsher environments. DCJ produces a pulsing jet of high velocity air flow, imparting momentum on the adjacent fluid creating series of counter rotating vortex pairs. The flow field produced by a DCJ has been numerically studied and has proven to be a complex function of the transient aero-mechanical interaction between the disks and the internal air volume. This study provides a unique insight in the air flow field of a DCJ by publishing time-resolved particle image velocimetry and displacement measurement results. These results show that the variable orifice nature of DCJ (2.5X area change) plays a key role in generating a difference between ingestion and expulsion velocity of as much as 8x, resulting in a new flow generated by the device. The study explores the effect of DCJ actuation frequency and its effect on the flow characteristics. The results aid to better understand the application of synthetic jets like DCJ and further help to advance future technology applications.