1 May 2005 – 31 January 2006
Total award $33,000
Flow control seeks to modify the flow so that it behaves in a different (favorable) fashion compared to no control. It may be used to control or promote boundary layer transition, limit flow separation, replace conventional Aerodynamic Control Effectors (ACE) providing significant stealth benefits, augment lift, modify acoustic emissions or reduce drag. The potential benefits of flow control are many and varied: reduced structural weight, greater resistance to battle damage and improved survivability (fewer components and linkages), improved performance (drag relates to the number of breaks in the aircraft’s external surface), greater flight envelopes (separation suppression), reduced operational cost (fewer components) and greater stealth capability.
Flow control may be implemented passively or actively. Active flow control is seen as a means to performance enhancement and a way to replace conventional ACE. Active methods for flow control include blowing, suction, moving surface elements, oscillatory blowing/suction, wall oscillation, vibrating ribbons, and zero-mass-flux, finite momentum actuators or Synthetic Jet Actuators (SJAs).
This research seeks to answer specific questions about active flow control:
- What characteristics are necessary for a flow control effecter to be functional in this application?
- What vehicle configuration would benefit the most from such an effecter?
- How can the effects of the flow control be modeled?
- What type of flight control laws and feedback mechanisms would be necessary to control the aircraft via flow control actuators?
- How would using non-conventional flow effecters improve aerodynamic performance?
In this research, we develop and implement active flow control in an unmanned aerial vehicle (UAV) configuration to show how the design and application of active fluidic control may be used to improve the performance of a proposed UAV. The fluidic control is implemented using a combination of SJA and trailing edge continuous blowing (or SJA’s). The flow control may be used to extend the angle-of-attack envelope by suppressing flow separation and to achieve hingeless control by modifying the wing’s circulation through trailing edge flow manipulation (using a modular jet flap or circulation control). At high incidence, upper surface flow control using SJA’s is used to re-attach the flow while trailing edge blowing is used to achieve control authority. Our SJA design is well validated and has been shown to be reliable and effective in many investigations. Proposed methods for achieving aerodynamic modeling, sensors for feedback to aid in control, as well as control law are investigated.
Specific tasks and research objectives:
- Determine a suitable actuator and implementation for flow control.
- Unmanned aerial vehicle conceptual configuration layout.
- Feedback methodology and implementation.
- Modeling of effects of proposed ACE.
- Control law design.
- Performance improvement estimates.
- Demonstration of key technology: ACE effectiveness.
Working with me on this program is Graduate Research Assistant:
- Monish D. Tandale