Active control of aerodynamic wing loads Through numerical simulations and wind tunnel tests, EU-funded researchers have developed and evaluated new concepts for the active control of aerodynamic loads on aircraft wings. Industrial Technologies © Shutterstock The main objective of the EU-funded project STARLET (Basic wind tunnel investigation to explore the use of active flow control technology for aerodynamic load control) was the alleviation of excessive aerodynamic loads that occur in rapid manoeuvres and other off-design conditions. As an alternative to conventional, mechanical solutions, such as symmetrical aileron and spoiler deflection, the STARLET team proposed a series of cutting-edge fluidic devices. Among the numerous concepts explored, the most promising were the fluidic spoiler, the so-called leaky wing and the dual trailing-edge nozzles. The fluidic spoiler consists of an array of mini-nozzles located at the upper wing surface tip. Air blowing from these nozzles influences the general flow around the wing, leading to its separation. As a result, bending moments acting on the wing structure are alleviated. Ducts connecting the upper and lower wing surfaces comprise its simplified version, the leaky wing system. When the ducts are open, air blowing through these ducts influences air flow on the upper wing surface, leading to its separation and, ultimately, the alleviation of aerodynamics loads on the wing. The third concept of two, upward-directed nozzles at the wing trailing edge exploits the Coanda effect to change the air flow around the wing. The redistribution of aerodynamic loads achieved can result in up to 30 % reduction of the bending moments acting on the wing root in the case of a sudden gust of air. The main advantage of the use of these fluidic devices is the significantly faster alleviation of aerodynamic loads on aircraft wings, compared to conventional, mechanical devices. However, the expected benefits are numerous and include the possibility to reduce the wing structure weight and thus the fuel consumption. For these innovative fluidic devices for active load control, three patents have already been filed, which may give birth to further developments in the future. The STARLET project has also been awarded the first prize in the Clean Sky Forum that took place on 17 March 2015. Keywords Wind tunnel tests, aerodynamic loads, aircraft wings, STARLET, flow control, fluidic devices
