Fluid Dynamics & Aerodynamics

Biography

Biography: Josep M Bergada

Abstract

It is well known that modifying the boundary layer separation point involves the modification of the forces acting onto a given bluff body. Traditionally, the separation point was usually delayed using passive flow control devices. Cars, trucks and aeroplanes have many of these devices. Quite recently, it was realized that the use of active flow control devices was producing very similar effects, having the capability of being switched on and off at users will and therefore implementing a new degree of freedom in the system where they are inserted. Regarding active flow control (AFC) devices, there are many possible configurations. AFC can be implemented using steady blowing or sucking, yet many researchers have observed that periodic forcing interacts more deeply with the boundary layer, therefore producing a huge modification to it and to the flow main parameters. When considering periodic forcing, it is relevant to evaluate the different fluidic oscillators, among them, the synthetic jets and fluidic actuators are the ones being more extensively used. During the presentation, some novel characteristics on fluidic actuators will be presented. Once the forcing device is chosen, the next step is to determine the location or locations the grooves need to be inserted. Groove location depends on the forcing system employed, forcing frequency as well as the momentum coefficient associated to the jet. At this point of the speech, some examples will be provided clarifying the effect onto the boundary layer and the downstream vortex shedding of several (AFC) devices. For some given applications, the optimum parameters regarding groove location, width, velocity ratio, etc., will be stablished. The speech will finish giving a list of possible future applications of (AFC).