The Aerodynamicist’s Eye
Laser tomoscopy is a flow visualization technique used in wind tunnels. Smoke particles illuminated by a laser light plane reveal turbulence, separations, vortices, etc. An anthology of image and video applications.
Aerodynamics engineers sometimes participate in experiments in the core of the wind tunnel ... if the wind is not too strong.
Laser tomoscopy in wind tunnel L2 (Lille) to test the wind resistance of solar panels intended to equip the first "industrial" floating photovoltaic power plant in the world, near Tokyo (Ciel et Terre Company).
Principle of laser tomoscopy
According to Jean Délery’s course on flow visualization
The laser beam is expanded with a cylindrical lens and converted into a light plane a few millimeters thick, which "cuts across" the flow area. The flow is seeded with white smoke created with a mixture of water and oil in a generator. These are technologies used in the world of entertainment.
Laser tomoscopy is a qualitative method. It allows separations, vortices and turbulent areas to be revealed, in order to understand the structure of the flow and also to prepare further measurements with a hot wire anemometer, or a laser velocimeter for example.
Laser tomoscopy is a visualization method for high-speed flows, up to supersonic speeds.
Wake vortices
Visualization of the wake vortices of a transport aircraft model catapulted through a curtain of smoke illuminated by a laser plane. Catapult bench, Lille B20.
Spin
Flow visualization on the upper surface of a fighter aircraft model simulating spin. Note that the tomoscopy device is attached to the moving model.
Insect wing aerodynamics
The film images are obtained in a laser plane located at ¾ of its breadth, using smoke emitted through an orifice. The shot rates are 2500 frames per second (the vibration frequency of the wings is of the order of 100 Hz). The film reveals, in particular, the interactions between the vortices emitted at the leading edge and trailing edge when hovering.
The wing, the size of a fly, stuck on a shaker.
3D vision
3D Visualization of vortices on the upper surface of an incident delta wing model using laser tomoscopy (several laser planes)
Environmental aerodynamics
Visualization of air currents due to wind around a material (sand) protection dome for public works (Feramus Company) - L2 wind tunnel (Lille)
Naval Aerodynamics
Tomoscopic visualization of wind effects around a frigate (DCNS) model - Wind tunnel L2 (Lille).
Train aerodynamics
Study of crosswinds flowing over train cars in the L2 wind tunnel in Lille. The seeding of the flow is directed towards the areas of interest using a cane (Arbel-Fauvet-Rail Company).
Supersonic flow
Visualization by laser tomoscopy of vortices generated on a missile at Mach 2