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Advance Laminar Flow Control with Variable Porosity

Project description

Mathematical methods fill in experimental gaps in wind tunnel tests of laminar flow control

Reducing turbulent air flow over air foils is fundamental to safe, efficient flight that minimises fuel consumption. Laminar flow control techniques are aimed at ensuring that the air is moving in a very orderly way over the air foil, as if moving in infinite smooth parallel layers. Developing these systems requires testing, and testing of such large structures requires wind tunnels equipped with the appropriate hardware and software to run the test, collect the data and analyse it. The EU-funded ALVAR project is testing a promising laminar flow control system in one of the world's largest low-speed facilities. The team is developing analysis methods able to extract local flow rates (not measurable experimentally) with very well-defined uncertainty levels, leading to a comprehensive evaluation of suction on the surface of the air foil.


Laminar Flow Control by means of a suction system appears to be one of the most promising technologies to significantly reduce the pollutant emission of modern large transport aircraft through drag reduction. The consortium, composed of a renowned University (TUBS) and world leading wind tunnel provider DNW, will perform high-quality large-scale wind tunnel tests with a full-scale vertical tail plane equipped with a hybrid laminar flow control (HLFC) system, which is based on the tailored skin single duct (TSSD) concept.
The DNW-LLF is one of the world’s largest low speed facilities and offers unique capabilities for wind tunnel tests with large scale models at representative flow conditions. The framework provided for by ALVAR includes state-of-the-art data acquisition, aerodynamic data, lift, drag, static pressure distributions, transition location with infrared and hot films, and the extremely high flow quality of the LLF 8x6 m test section configuration.
One of the root problems in wind tunnel tests with hybrid laminar flow control is that it is technically unfeasible to actually measure the local suction flow rate over individual surface areas, but only the overall suction flow rate including a number of additional values, such as pressures at certain locations, is feasible. However, the local flow rate can be post processed based on a complex measurement chain, employing data mappings (e.g. calibration of the suction skin) and interpolation/extrapolation schemes. This makes the local flow rate prone to the propagation of uncertainties and errors. ALVAR will therefore provide a scientific analysis of the whole measurement chain to establish a precise uncertainty of the local flow rate. Based on this, and through analysis, the design, optimization and implementation of the main mass flow meter including a proven pumping system to provide stable suction rates a comprehensive quantification of boundary layer suction will be performed by ALVAR.



Net EU contribution
€ 258 500,00
Universitaetsplatz 2
38106 Braunschweig

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Niedersachsen Braunschweig Braunschweig, Kreisfreie Stadt
Activity type
Higher or Secondary Education Establishments
Other funding
€ 0,00

Participants (1)