CORDIS provides links to public deliverables and publications of HORIZON projects.
Links to deliverables and publications from FP7 projects, as well as links to some specific result types such as dataset and software, are dynamically retrieved from OpenAIRE .
Deliverables
Active Suction by a perforated plate/single-cavity arrangement and Hybrid Control always resulted (at suction rates considered realizable in aircraft installations) in an increase in total drag due to the dominating influence of the increase in viscous drag caused by the cavity and the amplification effect of the sustained rear adverse pressure gradients on airfoils and wings. The buffet boundary was, as in the case of passive control, positively affected.
Discrete Suction leads, if applied upstream of the shock even at feasible suction rates (here CQ 0.0009), to drag reductions of up to 7.5%. Pump drag accounts for about half that gain with a net drag reduction of 4% remaining. Applying suction at the foot of the shock or further downstream is less effective in reducing drag, but more efficient in delaying buffet onset with maximum gains in lift at buffet onset of 5%.
Bump Control in the shock region was found to be the most effective control mechanism investigated with airfoil drag reductions of up to 23% at near-design conditions for laminar type airfoils and, similarly, at off-design for turbulent ones. In case of the infinitely swept sheared wing, drag reductions were slightly less due to the lesser contribution of wave drag to total drag. The effectiveness of bumps is, however, dependent on free stream conditions, i.e., on the position of the shock relative to the bump and on shock strength, suggesting an adaptive bump as the most effective device. Contour bumps were also found to have a positive effect on the buffet boundary with increases of up to 10% in lift at buffet onset for bumps located downstream of the shock. The effect of a bump in combination with upstream Discrete Suction was found to be additive.
Concerning control benefits, it was found that for an A340-type HLF-wing Aircraft a variable-height bump resulted in savings in fuel consumption on typical long-range missions of up to 2.11%, corresponding to reductions in Cash Operating Costs (COC) of 1.3%. For the aircraft with an existing turbulent wing, the range of bump effectiveness is rather limited due to the large shock movements associated with turbulent wings, and the inherent low wave drag at design. The benefits are, therefore, also limited with reductions in COC amounting to 0.4% for a retractable bump. Higher gains can be expected if off-design flight conditions, which are, in praxis, unavoidable, are included in the mission profile.
For a Regional-Jet with a laminar wing, based on the DRA-2303 airfoil, aircraft drag reductions of up to 6% were achieved near design due to bump control, while with an existing turbulent wing, only the operating range of the aircraft could be enlarged. Concerning installation penalties, it was determined that for an adaptive bump a drag reduction of 3% is required to offset the penalties, while for a suction system installation, a "zero-benefit" drag reduction of 6.8% is required; the former is quite achievable, while the latter, following the results obtained within the present project, seems hard to realize. These results should be considered preliminary and applicable foremost to the aircraft and the specific system installations considered.
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