The goal of the proposed GOALI investigation is to understand the dynamic coupling between "synthetic jet actuators" and the flow fields they can influence. Synthetic jet actuators are devices that in this case will be embedded just below the surface of a wing and produce small jets of air that interact with air flowing over the wing to produce a desired change in the performance of the wing, such as a reduction in drag. The outcome from achieving this goal will be insights and guidelines needed for design, development and optimization of synthetic jet actuators for active flow control applications such as drag reduction and lifting-surface performance enhancement in fixed and rotary-wing aircraft. Initial model validation experiments will be conducted on flows over flat plates, first with a single jet and then with an array of synthetic jets. Then, in conjunction with students spending time over summers conducting components of their research at Boeing, we will develop synthetic jet actuators tailored for use in arrays and optimized for control of two distinct flow fields of importance to our industry partner: flow over an airfoil and flow over helicopter airframe components. The Broader Impacts of the proposal include a dynamic partnership of academia and industry that will inspire students and will facilitate technology transfer. Students will work closely with industry co-PI Clingman, who will visit campus several times a year and participate in weekly conference calls and web meetings. Students will also have multiple opportunities to work in Boeing labs. Lastly, the societal and economic impact of enabling next generation aircraft by realizing the proposed active flow control capabilities is enormous
The goal of the proposed GOALI investigation was to advance understanding of the dynamic coupling between synthetic jet actuators (SJAs) and the flow fields they can influence. Initial model validation experiments were conducted on flows over flat plates, first with a single jet and then with arrays of two and three synthetic jets. Our GOALI collaborations included weekly teleconference meetings and having two Master’s Degree students who spent time at Boeing during the summer working design and development of motors for driving synthetic jet actuators. The first attached image illustrates one of the dual actuator design concepts tested and used for validation of computational studies. The second attached image shows computational fluid dynamics simulation of SJA output velocity. The third attached image shows computational fluid dynamics simulation of the output from three closely spaced SJA actuators operating in phase. The fourth attached image provides computational simulations of the interaction of SJA output with cross flow that suggest phase differences in the input signal to the actuator will significantly alter the resulting cross-flow field. The fifth attached image shows time average contours from particle image velocimetry experiments. The upper left is the baseline case of flow over a backward-facing step, i.e. with no SJA operating, and the other images show the influence on the cross flow and wake over the step when operating the jet to achieve jet to cross-flow velocity ratios, R, of 1.9, 2.1 and 2.3 as indicated. These results have application to scenarios such as reducing pressure/profile drag associated with flows over this relatively common geometry (imagine the rear of a minivan or large truck body). Pressure recovery downstream of the lower left image is roughly one half that of the baseline case, and of interest, for the velocity ratio of 2.3, slightly above the best experimental case, the drag is increased rather than reduced. The sixth attached image is a photo of one of our annual outreach activities, in which students from Prof. Flatau’s research group gave talks and demonstrations at Parkland Magnet Middle School for Aerospace Technologies.
