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Content archived on 2024-06-11

Hybrid laminar flow technology


Objectives and content:

Flow control is the ability to change a flow field in the desired manner. Drag reducing technologies like laminar flow control are of immense importance in economical and ecological terms. The acceptance of aircrafts by the airline customers heavily depends on economical (ticket price!) and ecological (environmental friendliness} facts. As it is well known, friction drag of commercial aircrafts reach more than 5036 of the total drag. Friction drag reducing techniques therefore offer large benefits. Previous European funded programmes (ELFIN I and II, LARA and HYLDA) were directed towards obtaining a better understanding the aerodynamic processes involved in boundary layer stability, developing and verifying mathematical tools for transition prediction, and a first investigation of manufacturing and system related issues. But despite all the progress laminar flow technology is currently envisaged as not being sufficiently mature to be applied in the short-to-medium term. Because within the EU project HYLDA we approach the status of the HLFC nacelle demonstrator readiness and the HLFCf in proven in flight status, the next logical and mandatory step is to work on more operational and manufacturing related issues. The strategy of HYLTEC is directly aimed to improve the clarification of practical problems of HLFC equipped aircrafts (on new ones or retrofitted ones). In formulating this proposal several problems related to these issues have been identified where the current knowledge envisaged for HLFC application problems are either inadequate or not proven. The work packages have been grouped in three tasks.

The HYLTEC activities will be divided into three tasks. Task one treats manufacturing, 5ystems and operational issues that are seen as problems or risks relating to the adoption of Laminar Flow Control on production aircraft. The content of this task can be broadly divided into topics related to Contamination and Manufacturing. Anti or De -Contaminations linked to the need to maintain the airflow surface in a suitable condition to ensure that Laminar f low can be guaranteed when required manufacturing issues revolve around the need to manufacture leading edges with porous suction surfaces to very close dimensional tolerances and to ensure that these tolerances are maintained throughout the operational life of the aircraft. Laboratory and flight demonstration of methods will be undertaken to validate the theoretical studies. The work of task two will be devoted to retrofit requirements for the application of HLFC to aircrafts. New products and derivative Products will continue to be developed to meet market needs without up-front application of laminar flow. However, the industry must retain a long-term awareness.

in order to protect the future competitiveness of new and derivative products it might be prudent to take account of the potential for retrofit of HLFC in the initial design phase. This task seeks to establish a general baseline approach to support designing for HLFC retrofit.

In order to apply P1LFC on a commercial aircraft in a reliable manner, a lot of technical aspects have to be clarified in wind tunnel campaigns and in flight tests. Task three will tackle specific aspects in relation with wind tunnel and flight tests. The ELFIN 11 test demonstrated with clear success the possibility of large regions of laminar flow even under wind tunnel conditions. The analysis of the ELFIN II test (done in HYLDA) and the flight test data - analysed partly in HYLDA - are the input for this task. The HYLTEC measurements are especially devoted to problems in conjunction with icing, contamination problems and in conjunction with HLFC related constraints for the retrofit issue. The goal of task three is to combine this information and the output of the HYLTEC wind tunnel test with specific issues treated by task one and task two to improve the HLFC related knowledge. BE97-4451

Call for proposal

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EU contribution
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Kreetslag 10

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Participants (14)