Focus on subsonic wind tunnels, aerodynamics in action

There are seven. The subsonic wind tunnels at ISAE-SUPAERO are lined up in a room where students, doctoral students and researchers meet. Their function? To reproduce airflows, like those that suck in the wings of an aircraft, and enable them to be measured.

"This is where students learn about external aerodynamic metrology," explains Patrick Chèze, head of the technical group in the Aerodynamics, Energetics and Propulsion (DAEP) research department at ISAE-SUPAERO. In other words, the measurement and interpretation of pressure and forces related to the flow of air over an object, such as an aircraft wing profile.

Students of the Ingénieur and Masters programmes can for instance practise measuring drag, the force that opposes a vehicle’s trajectory, and empirically look for solutions to reduce it. Or they can identify and measure the turbulence created at the back of a wing. "It’s a real educational test bed on which they learn the rigours of the test engineer’s job," notes Patrick Chèze.

Measuring aerodynamic pressure or force

The seven wind tunnels are standardised for practical work and operate in the same way: "The surrounding air is sucked in and compressed to give it a certain speed over the measurement section," explains Adrien Thacker, aerodynamics test bench engineer at DAEP. This measurement section, known as the test section, is the removable part of the wind tunnels. This is where a model is placed (cylinder, aircraft wing profile, miniature car, model aircraft, etc.) connected to pressure sensors or a balance that measures aerodynamic forces. Once the wind tunnel is running, the pressure or force measurement data is displayed on a screen.

Since this year, one of the wind tunnels has been reserved for small student projects. Lucas Nouveau-Duquesnes, a student on an apprenticeship speciality engineering course, is for example measuring the speed of vortices created at the tip of an aircraft wing, using a model that he has printed using 3D prototyping.

A team of four people (an engineer, two technicians and a fitter) is attached to the subsonic wind tunnels within DAEP’s technical group to ensure that this equipment operates smoothly on a day-to-day basis. "Our role is to prepare and set up the metrological data acquisition chain: calibrating and wiring the instruments, programming their control, setting up the study models and ensuring that the installations are working properly, and finally checking the measurement data", explains Adrien Thacker.

35 research projects each year

Their work is however far from routine! "As well as managing practical work for students and trainees in vocational training, we set up projects for lecturers and researchers. These involve experimental installations and high-precision set-ups, which often force us to be innovative and go beyond what we have already achieved. For example, to be able to recreate in a wind tunnel the effects of air flow disturbances on aircraft wings that they are trying to understand better."

No fewer than 35 research projects are carried out each year on DAEP’s wind tunnels and test benches by teacher-researchers from the Institute. "And one week of testing means three months of preparation for the technical team. So we’re involved in the research projects, and that’s really exciting!"