ADAPTIVE SHOCK CONTROL BUMPS

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The rising demand for air travel requires the engineering community to improve the aerodynamic efficiency of aircraft, especially in the context of tightening emission regulations such as the Vision 2020 directive. The plateau reached in the refinement of airframe technology in the last few decades has shifted the research focus on flow control devices such as shock control bumps (SCBs). Other flow control techniques include variable camber aerofoils, or the use of suction and vortex generators, but, as the two EUROSHOCK programs have highlighted, shock control bumps are one of the most promising shock control systems (Stanewsky et al. 1997, Stanewsky et al. 2002).Shock control bumps have the potential to improve the performance of transonic wings through the manipulation of the airflow over the suction surface. They generally take the form of small local deformations consisting of a ramp upstream of the nominal location of the normal shock wave, which generates near-isentropic compression waves and bifurcates the normal shock, followed by a tail, which brings the flow back to the aerofoil surface (Bruce and Colliss 2014). Shock control bumps can either be 2D or 3D. In the first case, the bump profile is constant along the span; in the second, several bumps are placed along the wing.One of the main issues associated with (both 2D and 3D) shock control bumps is that the beneficial smearing effects and stagnation pressure savings achieved at design are accompanied by an increase in drag off-design, when the position of the shock wave relative to the bump crest has changed.