Aviation is responsible for 12% of CO2 emissions from all transport sources. About 80% of these emissions are caused by flights beyond 1,500 kilometers, for which there is no practical alternative mode of transport, e.g., intercontinental or long-haul flights. Besides carbon dioxide, aircraft also emit noise, heat, particulates and gases such as nitrogen oxides which also contribute to the climate change. The aeronautical community is aware of the environmental impact of aviation, especially when the aforementioned increase of air traffic is considered. To take responsibility, the Advisory Council for Aviation Research and innovation in Europe (ACARE), was set up by the European Commission and formulated several ambitious goals in the European Vision “Flightpath 2050”. These include (but are not limited to)
compared to the capabilities of typical new aircraft in the year 2000.
The public-private partnership between the European Commission and the European aviation industry Clean Sky 2 is intended to make the main contribution to achieving these goals. With the HLFC-Win project, Clean Sky 2 LPA (Large Passenger Aircraft) focuses on the development of an innovative wing concept. One major field of research and development of environmentally friendly aircraft is higher aerodynamic efficiency. The objective is to reduce the drag for the lift needed. Drag is the aerodynamic force that the engines have to overcome in order to propel the aircraft. Therefore, less drag results in less fuel consumption, which in turn reduces the CO2 and NOX emissions. The project partners design in HLFC-Win an HLFC LE (Hybrid Laminar Flow Control Leading Edge) for an innovative wing concept with a Krueger high-lift system. HLFC offers a way to reduce frictional drag by delaying the laminar-turbulent transition of the boundary layer and thus has a significant positive impact on the aerodynamic efficiency of an aircraft. An aircraft with HLFC applied on the wings would require somewhere between 2 to 5 tons less, each flight. Scaled to annual values, HLFC is able to save 1 to 2 thousand tons of fuel per aircraft. That translates to more than 3 thousand tons of CO2 saved. The application of HLFC on the wing requires a microperforated leading edge skin, a load-bearing substructure with integrated ice protection and an economic manufacturing process achieving, gaps and steps with tight tolerances associated with laminar flow. In order to achieve a reliable proof of concept justifying to carry on the development of such technology, a ground-based demonstrator of such a leading edge up to the front spar will be build. In HLFC-Win, the researchers focus on a successful overall integration of HLFC on the upper side of the wing and aim to develop a long-term economic design by including life cycle analyses as early as possible in the design process.
The DLR Institute of Aerodynamics and Flow Technology supports the highly multidisciplinary development process by