TsAGI investigates a method to increase the flow rate in a wind tunnel
13 October 2020
Calculations for velocity field (on the left) and turbulence energy of the flow in the open test section of the T-03 model wind tunnel
Unique facilities, which has no analogues in the world, is a hallmark of the Central Aerohydrodynamic Institute named after Professor N.E. Zhukovsky (a part of NRC “Zhukovsky Institute”). Today, in an effort to meet the challenges of technological progress, TsAGI specialists modernize them gradually. Thus, within the framework of the Stend-2021 research project, they are investigating the method to increase the flow rate for the promising T-204 wind tunnel.
One of the features of open wind tunnels is the vibration of structural elements due to low-frequency pulsations of the flow, which leads to a significant limitation of its speed. TsAGI scientists faced this problem when creating the first open wind tunnels, including the T-101 and the T-104. Considering that the future T-204 wind tunnel should have a significantly higher flow rate than the mentioned facilities, the problem of pulsation becomes very urgent and should be principally solved at the very design stage.
’For the sake of solving this problem, it was for the first time that we studied in detail the effect of vortex generators of different geometry on jet boundary layer (mixing layer), as well as its interaction with the diffuser inlet; to this purpose we used modern flow research methods (PIV, hot-wire anemometry). We managed to obtain results that indicate the effectiveness of this method for experimental facilities of this class’, said Nikolai Batura, Head of Design of Wind Tunnels and Strength Test Facilities of TsAGI.
The effect of vortex generators of various shapes (triangular, rectangular) on the turbulence structure of the mixing layer was studied in the T-03 wind tunnel, which is a model of the future T-204 wind tunnel. As a result, it is shown that triangular vortex generators can significantly (up to 40 percent) reduce the energy of the turbulent component of the flow in the mixing layer. At the same time, the aerodynamic drag of the jet is reduced, due to which the speed of the flow is increased by
Based on the obtained experimental data, they developed a mathematical model which thoroughly describes the characteristics of the turbulent flow in the jet mixing layer. It will be used for the calculations when designing the open test section of the T-204 wind tunnel.
The promising T-204 subsonic wind tunnel, designed by TsAGI specialists, is intended to replace the outdated T-104 wind tunnel, created in 1939. The new facility will have dimensions similar to the T-104, a higher flow rate (140 m/s for an open test section and 160 m/s for a closed test section). At the same time, unlike its predecessor, it will be low-noise and suitable for acoustic research.