Flow-Interactive Control of a Flexible Wing Using Aerodynamic Distributed Bleed Actuation
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Peyredieu Du Charlat, Gabriel
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Abstract
Controlled interactions between a 3-D flexible wing model and the embedding cross flow were explored in wind tunnel investigations for effecting tunable structural and aeroelastic characteristics by exploiting regulation of the aerodynamic loads that are effected by fluidic actuation. The aerodynamic loads are regulated using distributed autonomous air bleed that is driven through surface ports and the wing’s inner structure by pressure differences between its pressure and suction surfaces and is regulated by surface louvers. Assessment of the control authority of time invariant bleed showed that prescribed decrements of the aerodynamic loads could be varied bi-directionally relative to a prescribed operating point by regulating the surface porosity of the actuation. The physical mechanism by which distributed bleed affects the aerodynamic loads was investigated using planar and stereo PIV measurements and it was demonstrated that time-invariant bleed affects the balance of CW and CCW streamwise vorticity in the near wake leading to variation in the sectional circulation that is associated with a decrease or increase in spanwise loading. It was also shown that spanwise-compact bleed actuation can induce spanwise-limited changes in sectional load distributions that can be exploited for spatial modifications of the wing’s apparent structural characteristics. This form of local bleed control can lead to buffering of three-dimensional flow effects along the span including local attachment and variation of the spanwise flow. While the wing’s response to temporal (top-hat) bleed actuation is 106 convective times, the shorter characteristic response time of the circulation (8.2 convective times) points to reasonably broad band control. Furthermore, it was shown that circulation computed from streamwise vorticity distributions in the near wake is a viable surrogate for tracking unsteady load variations during actuation. The utility of regulated bleed-induced spanwise load distributions for aerodynamic structural control was demonstrated by the suppression of deliberate planform vibrations using real time feedback control. It was shown that up to 70% reduction in RMS wing tip oscillation was achieved along with comparable reductions in associated oscillations of the aerodynamic loads and moment with minimal penalties in lift and drag. These findings indicate that fast spanwise-inboard bleed-induced temporal changes in the spanwise load distributions over the wing that can be exploited for spatial modifications of its apparent structural characteristics and thereby control its aeroelastic characteristics for flutter or gust alleviation.
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2024-12-08
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Text
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Dissertation