New aeroacoustic wind tunnel officially opened

The new aeroacoustic wind tunnel is just one element in a comprehensive programme of investment in vehicle development being undertaken at the Sindelfingen site. Joining the climate tunnel taken into operation two years ago, and the driving simulator centre, it rounds off the new test facilities at the Mercedes-Benz Technology Centre. Immediately alongside it, a new technology centre for vehicle safety is also currently under construction.

“Our models are currently the world champions in virtually all vehicle classes as far as aerodynamic and aeroacoustic performance is concerned,” says Professor Dr Thomas Weber, responsible for Group Research and Mercedes-Benz Cars Development. “And world champions need the best training facilities in the world. Exceptional ride comfort thanks to low wind noise, excellent roadholding thanks to low friction and, of course, outstanding efficiency as a result of low wind resistance: our customers enjoy the benefit of all these factors. We realize this innovative high-tech aeroacoustic wind tunnel ensuring that we maintain this leadership position.”

Its excellent flow quality, very low background noise levels, sophisticated roadway simulation and high efficiency make the new aeroacoustic wind tunnel at the development centre in Sindelfingen one of the most advanced facilities in the world. It follows the so-called “Göttingen design”, whereby the air is redirected to the blower after the measuring section and then re-accelerated to 265 km/h. With a nozzle system of 28 sq. m this maximum wind speed cannot be reached by any other wind tunnel for cars. Extensive noise insulation measures are integrated to allow use as an acoustic tunnel where interior and exterior wind noise can be measured for the relevant test vehicle. Even at 140 km/h the air flows through the measuring section almost without a sound. These features make it the quietest aeroacustic wind tunnel in the world.

The centrepiece of the almost 20-metre long measuring section of the wind tunnel is the roughly 90-tonne 5-belt-system used to simulate various road conditions perfectly. The integrated turntable with a diameter of twelve metres enables the test vehicles to be subjected to a flow of air from a defined angle in order to simulate crosswinds realistically.

The traversing system enables the engineers to position a variety of aerodynamic sensors and microphones around the test object with a high degree of precision. This is a requirement for very precise aerodynamic measurements and aerodynamic optimization of the vehicles.

For almost three decades, the aerodynamic specialists at Mercedes-Benz have been breaking one record after another. The current world record is held by the new CLA-Class, in its BlueEFFICIENCY Edition guise, with a Cd value of 0.22 and a wind resistance area of 0.49 sq. m. The drag coefficient of the new S-Class improves on that of its predecessor by a further two hundredths – with a Cd value of 0.24 it not only sets a new benchmark in its segment, but is the best saloon overall in this respect. The S 300 BlueTEC HYBRID is even more aerodynamic. The diesel hybrid model achieves a Cd value of 0.23 and, not least as a result of this extremely low wind resistance, delivers impressive fuel consumption figures of just 4.4 l/100 km, or 115 g/km CO2/km.

The forthcoming generations of vehicles, along with all-new electric and hybrid vehicles from Mercedes-Benz, will continue this trend by being aerodynamically honed in the new wind tunnel. In the case of electric and hybrid vehicles, low wind resistance takes on even more significance, as it has a direct impact on the achievable range per battery charge – while during recuperation too, more energy can be fed back into the battery.

Models from Mercedes-Benz also take the lead in almost all segments when it comes to aeroacoustics. The new S-Class not only offers the lowest level of wind noise in its segment, but is also quieter than that world champion of wind noise, the Maybach, so making it the quietest car overall. As well as the optimised design of the vehicle, significant improvements made to the body shell and to the door seal concept in this model series have been further factors contributing to the reduction in wind noise.

Mercedes-Benz was the first automobile manufacturer to have its own wind tunnel: the “large wind tunnel” in Stuttgart-Untertürkheim. On 5 February 1943 the first documented measurement was carried out there. The wind tunnel in Untertürkheim, which has been in the company’s ownership since the 1970s and was technically updated several times over the years, is still indispensable for the Mercedes-Benz developers, particularly for soiling analyses or windscreen wiper testing. And the “large wind tunnel” more than lives up to its name: for it is here that Mercedes-Benz commercial vehicles are also honed to perfection.

SOURCE: Damiler