Aeronautics, Automotive, building, sport,… all of these sectors have in common the use of aerodynamic wind tunnels for their studies and research. For more than a hundred years, French industry has been designing and optimizing its achievements thanks to the internationally recognised aerodynamic means that are available in France; The ONERA, CSTB and the S2A3 economic interest group are the main players. Inseparable from experimentation, measurement techniques and numerical modeling have progressed extraordinarily in recent decades, leading to a revolution in the experimental approach.
The wind tunnels, 100 years after Gustave Eiffel
By Bruno CHANETZ, Master of research, ONERA
At the dawn of the twentieth century, the wind tunnels were imposed by allowing, according to the happy formula of Gustave Eiffel, to pass: from the flair of the builder to the art of the engineer. The wind tunnels, subsonic to the origins, then Sonic, supersonic and hypersonic, allowed to accompany the development of all the aircraft of the twentieth century, planes to the rockets, not forgetting the buildings, the cars,…. However, at the end of this century, the progress of numerical simulation linked to those of computational power, appeared to threaten their growth. Today, the large wind tunnels, always very operational, remain strategic in response to the new environmental challenges for the economic and ecological development of the French industry.
The aerodynamic measure, from Pitot to the vision of the unseen
By Benjamin LeClaire, Master of research, ONERA
In recent decades, the methods of measurement to characterize flows around the forms and to determine the stresses induced by the flows on them, have evolved dramatically. This is particularly the result of technological advances in lasers and cameras, as well as those made in automated image processing. While traditional methods such as Pitot probes are still used, the speed and density measurement techniques of the most advanced flows are non-intrusive and rely on intense illumination and visualization of The flow to be measured, possibly inoculated with very fine particles. These techniques then give access to quantities of information, as well as to the fineness of structures becoming comparable with those of numerical simulation results, which nourishes and enriches the computational-experience dialogue.