Executive Summary : | The synthetic jet is one of the emerging technology for thermal management, active flow control, thrust vectoring, delaying boundary layer separation, and mixing enhancement. When compared to continuous jets (CJs), SJ performs better in the near field due to the formation of vortices that entrain the surrounding fluid towards its core. However, issues such as low volume flow rate and a significant decrease in vortical strength in the streamwise direction make SJ less efficient in the far downstream. As a result, the synthetic jet array (SJ array), a novel approach of assembling multiple orifices, is presented to alleviate the problems associated with single SJs. When the (SJAs) are driven independently, the volume of the jet will rise, which is directly proportional to the number of actuators. The independent operation of an SJ array offers an additional feature of vectoring the jets towards a required direction. The high volume flow rate and the controllability action of synthetic jets can solve many heat transfer problems by cooling a wide range of surfaces. The miniaturization of electronic devices sometimes leads to a high internal heat generation on a specific junction, requiring high-intensity spot cooling over that surface. A conventional jet-based device, when employed for cooling, achieves higher Nusselt numbers only at the stagnation region, whereas the Nusselt Number reduces drastically as we move away from the stagnation region. In most jet impingement-based cooling devices, the stagnation region is fixed unless the orientation of the jet is changed. In the case of nonuniform heat-generating electronics circuits, the hot spots are both a function of space and time. A conventional jet, including a synthetic jet, is not useful for mitigating hotspots. Hence, there is a need to propose a new technique that can mitigate hotspots without complexity. Inspired by this application, we propose for the first time a new device based on a synthetic jet array, which can steer and focus the jet at the desired location. This novel device can steer and focus the jet by manipulating the amplitude and phase delay between the individual actuators. Such a device may find equal applicability in other applications, like, as aerodynamic flow control and mixing enhancement. We have proposed a hypothesis to explain the phenomenon of steering and focusing of the jet. We have also conducted preliminary numerical simulations to test our hypothesis. The proposal intends to design and fabricate proof of concept device to demonstrate the steering and focusing of the jet. In the present proposal, we intend to conduct the following experiments: 1. Detailed flow field visualization and unsteady velocity measurement 2. Time-resolved particle image velocity measurements (PIV) to understand the complex vorticity dynamics. 3. Jet Impingement Heat Transfer Measurements using Infrared Camera 4. Demonstration of hot spot mitigation capability of the proposed device. |