Technology

Full Scale Aerodynamic and Aeroacoustic Wind Tunnel

"The wind tunnel facility in Orbassano, Italy, is a closed circuit type with ¾ open jet test section and two option for the nozzle exita area: 20 and 30.5m2 . It's equipped with a rolling road simulation system: this provides a 5-belts configuration: one central narrow belt, 6 meter length, 1.1 meter width, and four wheel spinning units. The main balance, to integrate the Rolling Road System (RRS), has an high accuracy, allowing less than 1 N about longitudinal direction. This configuration is common because it is considered the best compromise between flow simulation and efficiency to manage vehicle installation. The combination of boundary layer suction system effect and moving belt produces a nearly zero height displacement thickness (δ* < 0.5 mm) along the entire main belt. The four additional balances, under the wheel spinning units, are used to measure tangential forces necessary to keep constant rotational wheel speed and in this way to measure the sum of drag forces (mechanics, tyre rolling resistance and wheel ventilation)."

Photo of propeller in an aerodynamic tunnel

Aeroacoustics

The reduced background noise in the test chamber allows to perform vehicle aeroacoustic evaluation using acoustic dummies and microphones located inside the cabin. A combined beamforming system (2 external planar arrays and one internal spherical array) allows to evaluate the so called "shape noise", ta various velocity and yaw conditions: this gives indications about the main noise sources due to the vehicle shape details, in an objective way, and to quickly evaluate different alternatives. To complete, it's possible to mount accelerometers on specific elements, to put in evidence vibration contributions.

Flowfield Analysis

A traversing system, togheter with various probes, allows to investigate flowfield features around the shapes, with spacial resolution from 1 to 100 mm. The postprocessing phase, quickly available after the tests, makes available pressures and local velocities in the area investigated; in this way it's possible to better understand phenomena causes and effects and/or perform CFD validation.

Climatic Wind Tunnels

The climatic wind tunnels are of the closed-circuit type with a horizontal loop and semi-open chamber. The climatic cell drive cell, on the other hand, has more compact dimensions with a vertical air recirculation loop. The three structures offer a wide range of temperatures (from -45°C to 60°C), humidity, and the simulatation of solar radiation through an HMI lamp panel that reproduces the spectrum of sunlight. All facilities are equipped with a wind generation system up to a maximum of 180 km/h and a latest-generation 4WD dynamometer roller bench capable of accommodating cars and light commercial vehicles. It is possible to reproduce driving profiles of all types, from constant speeds to adjustable power or tracking variable speed traces provided by the customer. It is also possible to perform coast-down tests on the rollers to accurately reproduce the vehicle’s braking curve on the road. The climatic cell is also equipped with a soundproofing system that allows NVH tests to be carried out even in extreme climatic conditions.

Instrumentation

All facilities are equipped with a data acquisition system integrated with the wind tunnel control system, which allows recording and synchronization of all the values of the instrumentation installed on board the vehicle and the data flow of the vehicle’s CAN networks, to have a single output. HW/SW systems from IPEtronik, ETAS-INCA, and Vector are used.

Workshop

To support testing are available, the following are available:
A workshop department equipped with car lifts and mechanical tools, primarily used for the installation and verification of all necessary instrumentation on the test object.
Software and hardware systems for communication with the various types of CAN networks present in vehicles.
A laboratory for the management and calibration of various types of instrumentation for measuring physical quantities, including temperature, pressure, air speed, flow rates, voltage, and current.
A machine tool workshop for the customized creation of parts necessary for experimental activities.