Hybrid laminar flow control structures under bird strike - Analysis of a full-scale demonstrator within the frame of CLEAN SKY 2

Kurzfassung

Hybrid Laminar Flow Control (HLFC) has the potential to reduce specific fuel consumption, making future long-haul aviation more sustainable. This technology is based on reducing friction drag by maintaining the boundary layer attached to the external skin of the aero profile, delaying its transition to turbulence. The HLFC structure consists of a micro-perforated titanium external skin, adhesively bonded to an internal corrugated composite structure, creating a span-wise multi-chambered layout between the two parts, where suction is applied to activate flow control. In this study, HLFC technology is applied to a Horizontal Stabilizer Leading-Edge structure, fully representative of a horizontal stabilizer segment. During the certification process of a stabilizer structure with HLFC drag reduction technology, ensuring safety under impact conditions - such as bird strikes - is mandatory and must not compromise the overall safety of the aircraft. The integrity of the load-carrying structure and its capability for continued safe flight must be demonstrated. For the bird strike load case, FAA airworthiness requirements for transport aircraft (Part 25) were used as a reference, considering a 3.6 kg (8 lb) bird at cruise speed at sea level. Another important aspect of this study is the use of an artificial gel bird as a substitute for a real bird.