Turin Rotating Platform Facility

• Rotating platform equipped with a tank of 5 m diameter and 1 m depth for the study of turbulence in presence of rotation and stratification;
• Smooth platform movement over oil film, digitally controlled speed with a period between 3 s and 360 s;
• Optical access from the top and from the  lateral wall by several windows, three glass channels on the floor for accessing with lasers and/or with cameras;
• Turbulence generators including grids, rotating disks of different diameters, and complex obstacles on the bottom;
• 15 W continuous laser and cameras up to 500 Hz at resolution 1280x1024 for both 2D and 3D PIV and PTV.

The Turlab facility in Torino is one of the largest rotating platforms available for scientific investigations of turbulence in presence of rotation and/or stratification.

It was built by the University of Torino between 2004 and 2005 with an investment of 800 k€ for the experimental facility and 400 k€ for measurement equipment for a total of 1.2 M€. It is located about 10 m underground in the basement of the Physics Department. In addition to the tank room, the laboratory has several other rooms for supporting the experimental work, including a machine shop, a computer room and offices for guests. Technical support is provided by two full time technicians and one part time computer engineer. The tank on the platform, with an inner radius of 2.5 m, is provided with several windows on the lateral side and three glass channels on the bottom for optical access. A removable bridge co-rotating with the tank provides easy access to the top layer. It can be filled with homogeneous water or density stratified water up to a height of 80 cm.

The platform is moved by a three-phase electric engine and the tank floats over a thin layer of oil which ensures the virtual absence of any vibration. Platform speed is digitally controlled, together with acceleration and deceleration, the rotation period is between 3 s and 360 s. Different devices can be used to induce turbulence in the tank, including towed grids, rotating disks and water pumps. The tank is also used for studying the boundary layer over complex boundaries by introducing obstacles on the bottom. Illumination of the flow is provided by a solid state diode continuous laser (green) with maximal power 15 W. Laser sheet can be placed in any direction and almost any position in the tank thanks to the glass windows on the side and bottom. Measurement fields are up to 50x50 cm in vertical cross section and up to 140x140 in horizontal cross section.

The Turlab facility is equipped with several cameras. Dalsa cameras with resolutions up to 2352x1728 at 60 Hz and Mikrotron cameras with frequency up to 500 Hz at resolution 1280x1024. Both 2D and 3D PIV systems are available with Matlab graphical interface for calibration, velocimetry and analysis. The facility is also appropriate for Lagrangian measurements with different kinds of tracers. Storage hardware is composed of a cluster of HP servers (28 cores) with a 6 TB raid disk space for data analysis and storage. The laboratory has also two different acoustic probes for measuring 3D velocity components in a small sample volume with rates up to 200 Hz.