You have JavaScript DISABLED. This web site has been designed for browsers with javascript enabled and will not function correctly without it. For information on how to enable JavaScript CLICK HERE.
One end of the Volvo wind tunnel with aerodynamics expert Tim Walker by the side
A C30 inside the wind tunnel
Car manufacturers have been using wind tunnels for decades, ever since it was clear that the more streamlined the shape of the car, the less drag there would be and this would improve performance. Less wind resistance meant less power needed to achieve a desired speed which in turn reduced consumption of fuel.
Volvo Car Corporation has one of the world's most advanced wind tunnels today and the 20 million euro facility (originally built in 1986 and completely refurbished in recent years) is its new tool in the quest for lower fuel consumption and reduced carbon dioxide emissions. The wind tunnel is said to be the first one owned by a carmaker that fully simulates the airflow around and underneath the car's body, combined with wheel rotation on a flat road surface.
"Our investment is already paying quick dividends. We have succeeded in reducing air resistance in the new Volvo C30 DRIVe by more than 10%. This, in turn, leads to around 3 grams lower CO2 emissions per kilometre," explained Tim Walker, aerodynamics expert at Volvo Cars.
Translated into fuel consumption, this is a reduction by just over one-tenth of a litre per 100 kilometres according to the official EU Combined Cycle. Sounds insignificant but in real-world driving conditions where speed and therefore air resistance are often higher, the actual saving in fuel can be more than twice as high, perhaps in the region of 0.3 litre/100 kms. This means that a driver who covers 15,000 kms per year will save about 45 litres of fuel - almost a full tank in a C30. It's an economy benefit that is also appreciated by the environment.
"With a firm focus on environmental properties for the foreseeable future, our recently upgraded wind tunnel is going to be a particularly valuable tool. Aerodynamic improvements to the body and underside of the car will help us cut CO2-emissions across the whole model range," said Magnus Jonsson, Senior Vice President, Research & Development at Volvo Cars.
Since the underside and wheels account for more than 50% of a car's total air drag, a traditional wind tunnel where the vehicle stands still in a flow of air can provide an incomplete picture of the vehicle's overall aerodynamic properties.
"It's a bit like measuring the aerodynamic properties of a car that is standing still in a parking lot during a powerful storm. Our new wind tunnel, on the other hand, has been designed to exactly replicate the flow of air around and underneath the car when driving on a real road at speeds of up to 250km/h. It uses sophisticated techniques at the forefront of aerodynamics technology" revealed Mr. Walker.
The underside and wheels account for over 50% of total drag on the car
- Four flat steel belts that spin all the wheels.- One central (5.3 metres long and 1 metre wide) steel belt that simulates the road under the moving car.- An 8.15-metre fan with carbonfibre blades that generates wind velocities corresponding to road speeds up to 250 km/h.The test car is connected to a highly sensitive balance using four small struts. These struts hold the car in position while the weight of the car is transferred from the tyres to the balance via the flat steel belts.
"This makes it possible to load up the wheels and tyres exactly as they are when driving on the open road. The balance is so sensitive it reacts even if you toss the world's smallest mobilephone onto the front seat," said Mr. Walker.
In the EU Combined Driving Cycle, with an average speed of just 33 km/h, air drag accounts for just over one-quarter of total fuel consumption. At a steady 90 km/h, this increases to more than 50%. These figures indicate just how important aerodynamic efficiency is to the car's fuel consumption and environmental properties.
Tiny spoilers on the rear glass of the V50 help make a tiny reduction to CO2 emissions
When it comes to the new Volvo’s DRIVe models with CO2 emissions of 115 gms/km (C30) and 118 gms/km (S40 and V50) respectively, tests in the wind tunnel have resulted in small but effective changes to the front spoilers, under-floor panels, roof and tailgate/boot lid. The changes naturally vary depending on the individual model.
On the C30 DRIVe, for instance, coordinated refinements to the roof spoiler, rear bumper and under-floor panels have cut overall air drag by more than 10% compared with the current C30 1.6D.
"In the original wind tunnel, the focus was on the body. In the new one, we can obtain an overall picture that also takes in the underside and the wheels. Thanks to the better simulation techniques that the new tunnel offers we have probably improved the aerodynamic drag by a third. It is here that the major improvements will be seen in the future. I would call the forthcoming developments in underside and wheel efficiency a revolution. Up top, it's more about evolution," said Mr. Walker.
Talk about this article in the MTM Forum