Central Aerohydrodynamic Institute
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TsAGI Studies Adaptive Trailing Edge Wing Flow

29 June 2022

The nature of wing flow (i.e. laminar or turbulent) is an important issue determining an aircraft’s aerodynamic performance, stability, and controllability. This fundamental topic is being studied by scientists at TsAGI (a part of NRC “Zhukovsky Institute”). To obtain more test data on laminar-turbulent transition, the scientists tested a half-model of adaptive technology demonstrator. The tests were conducted under a state contract with the Ministry of Industry and Trade of the Russian Federation.

For these tests, the scientists used a relevant swept wing semi-model with an adaptive trailing edge capable of changing its geometry according to the mode or conditions of flight. The scientists’ choice of the semi-model was done purposefully: it has an increased wing chord which is 740 mm in length and its wingspan is about two meters. The scale allowed scientists to conduct the tests in nearly full-scale conditions. They successfully achieved high Reynolds number (i.e. the characteristic of flow conditions changing from laminar to turbulent) approaching 12 million. By comparison, this number ranges from 20 to 40 million for modern passenger aircraft while it does not usually exceed 5 million in wind tunnel test conditions.

Studies were conducted in the TsAGI transonic T-128 wind tunnel at Mach numbers from 0.5 to 0.8 (600-1000 kph, correspondingly). The specialists used simultaneouslys everal methods of streamline visualization: thermal imaging and liquid crystals. Combined together, these methods provided a clear picture of the laminar-turbulent transition on the wing.

‘We obtained the laminar flow which corresponds to nearly field conditions— we have achieved such results in transonic wind tunnel for the first time. The data will allow for not only studying the principles of boundary layer transition but also for verifying the computational methods that we are widely using. Apart from that, the results will become a reference providing clear capabilities of the wind tunnel related to laminar wing testing,’ said Anatoly Bolsunovsky, Head of Division, Department for Aircraft and Rocketry Aerodynamics, TsAGI.

TsAGI Press Service
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