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NLF Wing High Speed Performance Test

European Union
Complete with results
Geo-spatial type
Total project cost
€1 499 384
EU Contribution
€1 124 538
Project Acronym
STRIA Roadmaps
Vehicle design and manufacturing (VDM)
Transport mode
Airborne icon
Transport policies
Environmental/Emissions aspects
Transport sectors
Passenger transport,
Freight transport


Call for proposal
Link to CORDIS

The primary innovative approach and the major aim of the investigations being covered here was in the first instance to perform reliable and high-quality procedures for laminar wing testing under and near flight conditions at high Reynolds numbers in ETW. Beside confirming a number of already mature and successfully applied measuring techniques, these investigations validated a new evaluation process by quantitatively determining areas of turbulent flow on the wing, e.g. generated by turbulent wedges inside the laminar flow region. Calculating the difference in drag due to laminar and turbulent flow by post-processing forms a tool for correcting the overall drag as measured by the balance.

A second subject of interest was the surface quality of the model to be tested. Special attention was given to the cleanliness of the model on preparation and the eventual contamination while testing.

The experiments improved the understanding of the flow and the performance of airplanes and are an indispensable tool for airframe manufacturers. At the end, the project helped to save resources like fuel, to reduce the pollution of environment by exhaust gases and noise and finally to increase the safety of flights.


Parent Programmes
Institution Type
Public institution
Institution Name
European Commission
Type of funding
Public (EU)
Specific funding programme
JTI-CS - Joint Technology Initiatives - Clean Sky
Other Programme
JTI-CS-2013-3-SFWA-02-044 NLF Wing High Speed Performance Test


Executive Summary:

The EU project NLF-WingHiPer had shown the capabilities of the European Transonic Windtunnel for the high-speed testing of natural laminar flow wing configurations. The achieved high data quality was combined with an acceptable low number of turbulent wedges up to a Re number of about 18 mio.

A special aspect of the test campaign was to study the influence of given discontinuities (specified waviness and particles size of a transition fixing) and also any undesirable perturbation on the model surface (gap at the leading edge, escaping sealing material and contamination by inherent particles). The results are showing a high sensitivity on those influences and a need for extremely careful preparation of the model. In contrast to previous laminar test at ETW studies, the fidelity of the test object became dominant compared to the particle issue of the tunnel.

Higher Re numbers and thus a decreasing boundary layer thickness reveal the problem of adhering particles at the leading edge of the wing. Also the unavoidable contamination of the leading edge after a testing time in the order of hours is still a challenge. The measures taken until now to reduce the particle concentration within the tunnel were successful. The particle monitoring equipment is a good indicator for further improvements.

In order to correct the influences of turbulent wedges on the total drag of the model further parameter studies and correction algorithms are needed. The investigation with fixed transition at different height had given valuable instruction in this regard.

The project gave good pieces of advice for understanding of how to design natural laminar flow wings. In this context the testing of NLF configurations at flight Re numbers at ETW plays an essential role. Further research work is needed for a better understanding of transition phenomena at high Reynolds numbers.


Lead Organisation
European Transonic Windtunnel Gmbh
Organisation website
EU Contribution
€1 124 538
Partner Organisations
EU Contribution


Technology Theme
Aircraft design and manufacturing
Active flow control and interrelations with Reynolds stress
Development phase

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