Compact inlets with an S-shape have become widely used in aircrafts due to the numerous advantages compared to conventional ducts. However, due to their low length to diameter ration and low aspect ration, there are some flow phenomena, which are undesirable such as massive separation leading to losses in total pressure and secondary flow structures causing distortion at the Aerodynamic Interface Plane (AIP). These drawbacks need yet to be overcome in order to apply these ducts on a wider range of vehicles.
The inlet to an aircraft propulsion system is typically designed to supply flow to the compressor with minimal pressure loss, distortion, or unsteadiness.
The addition of active flow control devices, such as synthetic jet actuators, on three-dimensional aerodynamic surfaces (i.e. vertical tail, wings, etc.) can lead to significant flowfield modification for beneficial improvements in aerodyanmic performance. Previous work by Dr. Nicholas Rathay and collaborators on this project focused on augmenting the side force generated by synthetic jets through separation control on scaled vertical tail models. Since commercial airplane tails are sized based on a single engine failure situation, they are larger than necessary for normal flight.
This project is acutely focused on the fundamental fluid physics governing the unsteady loads experienced by non-streamlined objects. Bluff bodies, as they are commonly known, experience abrupt separation of the flow which subjects them to the consequences of flows which may be unsteady and in many cases, transitioning from laminar towards turbulence. Examples of bluff bodies include tall buildings, bridge decks, and slung-load containers. One archetype geometry which has proven itself to be a benchmark for other studies is the rectangular prism.
In general, the behavior in the wake of a wall-mounted circular cylinder with finite height is considerably different from that of two-dimensional bluff bodies. Unlike the flow field associated with a conventional 2D cylinder, a cantilevered finite-span cylinder is largely influenced by the presence of a spanwise (i.e., along the height of the cylinder) velocity component, most notably the downwash issued from the free end of the cylinder.
This project investigates the use of active flow control on square bluff bodies relevant to tall buildings. The research seeks to ameliorate the unsteady loading by controlling the formation and development of the von-Kármán vortex street, which is known to be the cause of undesirable building motion. More specifically, a fluidic jet is periodically excited at each of leading edges of a square prism where the shear layers separate and evolve into the large-scale vortex shedding in the wake.
Applying bio-mimicry intelligence to the aerodynamic performance of tall slender buildings has potential to lead to not only improved response to wind loading, but generate savings in material and construction costs, affect energy consumption by providing self-shading and controlling local air flow to promote local wind energy generation and ventilation strategies.