Why does the aerodynamics of a commercial vehicle the same time or perhaps even a larger role than in a Car? If you look at a Truck, then everyone is visually seen rather like a wall. Especially in the transport sector, the efficiency is but one of the key factors and so the fuel consumption or fuel efficiency cost for the maintenance. In a current Truck, spent about a third of the available mechanical energy by Burning fuel to Overcome air resistance. Every drop of Diesel in the must have less to be burned, so it is money for the freight forwarding company.
The wind tunnel at the Untertürkheim plant
A Truck like the Actros as efficiently as possible so to make, will worked extensively on the aerodynamics of the Trucks. The development is done virtually on the computer, but also real experiments in the wind tunnel. At the plant in Untertürkheim, Daimler AG has a wind tunnel. Already since 80 years in operation, and thus the oldest of the 1-to-1 wind tunnel in Europe. Thanks to targeted modernization, he is still on the current state of the art.
Nine-wing axial fan ensures the strength of the wind 17
The heart of the installation is a nine-wing axial fan with 8.5 meters in diameter. Each of the wings brings it to a weight of 850 kilograms. Powered by the wings of two DC motors, each with 2500 kW of power put to the fan so vigorous in movement, that even the wind can be given to strength of 17. In order for Tests can be up to a wind speed of 250 km/h on the plant.
Test range with a turntable
In the test area of the test Vehicle is on a turntable with twelve meters in diameter, so that it can be exposed to the wind stream at the front or at any other desired angle to the side. In the hub of a Six-component balance is integrated. It serves for the highly accurate determination of many forces, including the air force. The forces are transmitted through levers and rods to the load cells and thus can be evaluated made.
Tests in the wind tunnel for the new Actros with MirrorCam
The current Generation of the Actros has for the first Time about a MirrorCam instead of the classic outside mirror. The associated improved aerodynamics contributes up to 1.5 percent to the total saving in fuel consumption of the new Actros. Possible this was due to the intensive work in the wind tunnel. In the experiments simulated, the engineers, the flow conditions on the Truck, with the aim to determine the best Position for the camera arms of the MirrorCam. To the debate of the upper and the lower area of the A-pillar and the upper portion of the B-pillar stood.
For the Experiments a real Actros was used, which had replaced the exterior mirrors by means of prototypes of the camera arms – sequentially applied to test the three positions. The Truck was placed on the scale of the wind tunnel and the fan is set in motion. The scale allowed the engineers to measure the air force, which influenced the flow around the vehicle. Result: The best Position for the camera arms located on the A-pillar in the area of the edge of the roof.
Development for more fuel efficiency
The wind tunnel were also used for the development of the new concave-shaped trailing edge flaps on the cab. The new Dampers also contribute to that as little fuel is required to as possible. All of the aerodynamic improvements, together with the optimized cruise control and control Predictive Powertrain Control (PPC), as well as the new final drive ratio in the transmission, finally, the new Actros on highways up to three per cent, and in intercity traffic for up to five percent less fuel than its predecessor. Alone the MirrorCam contributes around 1.5% to the total fuel savings, what is the fuel efficiency contributes.
Pictures: ©Philipp Deppe / MBpassion.de