Testing facilities

Making weather in the climatic wind tunnel
Simulating wind and the road
A sunny outlook in the climatic wind tunnel
Technical data on Behr's wind tunnels
Searching for the “sound of silence” in the acoustics lab
Using modern technology to suppress noise

Making weather in the climatic wind tunnel
Behr’s engineers can thoroughly test their prototypes for air conditioning and engine cooling in three wind tunnels - two in Stuttgart, Germany, and one in Troy, Michigan Behr America . The climatic wind tunnels have enough space for large commercial vehicles and all the equipment to simulate a variety of climate conditions. Floor-to-ceiling ventilators generate wind speeds of up to 250 km/h.With our climatic wind tunnels we simulate all the world's climate zones, from an arctic -30°C to humid tropical conditions and even a desert-like +50°C. This is an important pillar for adapting new products
Products and services arising from our research and development work for actual system use.

The tests need to be well prepared so that the measurements in the wind tunnels also deliver the necessary results.Before the actual measurements take place, the vehicle is equipped with sensors and tested in the vehicle preparation area. In the temperature pre-conditioning area, the vehicles that are to be measured are brought to the desired temperature - from -40 to +50°C.After it has been prepared, the vehicle enters the measuring chamber, where it is exposed to the simulated wind and weather.

Simulating wind and the road
A quietly running blower ensures that the noise level in the measuring chamber does not exceed 70 decibels, even at wind speeds of 50 km/h. This level is significantly lower than that of conventional wind tunnels. Acoustic tests to examine the noise level in the cabin and ensure a pleasant acoustic environment are possible under these conditions.

As the pressure conditions around the entire vehicle are decisive for the airflow in the vehicle interior, the quality of the airflow in the wind tunnel is very important. In conventional wind tunnels, an outlet area of six square meters for vehicle tests is considered large; the vent in Behr’s climatic wind tunnel, with a flexible top section for commercial vehicles, can be set to up to ten square meters.

Two pairs of rollers are installed in the floor of the measuring chamber to simulate road conditions. They can be automatically set to the axle base of the respective vehicle. These dynamometers brake up to 150 kilowatts of engine output per axle and thus reproduce the road resistance. The blowers and rollers can be operated synchronously and are highly dynamic - in extreme cases, they can be braked from 130 km/h to a standstill within 6 seconds.

A sunny outlook in the climatic wind tunnel
The sun heats a vehicle differently depending on the time of day, season, and location. To exactly simulate this, Behr’s wind tunnels have one-of-a-kind solar equipment that can be set for every location and every time of day. The radiation intensity varies from 350 to 1200 watts per square meter, and the spectral distribution of the lamps’ light corresponds to that of the sun. The solar lamps are mounted on movable frames that can be tilted and lowered to generate any angle of incidence and the sun’s altitude at all times of the day. Shutter systems with filters are used to simulate shadowing effects from clouds or when driving through a tunnel.

Technical data on Behr's wind tunnels
Behr has climatic wind tunnels at two locations. The climatic wind tunnel in Stuttgart, Germany, has been in operation since 2000. In Troy, Michigan, engineers have been able to use the tunnel there for research and development since 2004.

Performance features	Troy climatic wind tunnel	Stuttgart climatic wind tunnel
Max. vehicle dimensions (L x W x H) in m³	8.8 x 2.6 x 4.35	10 x 2.65 x 5
Max. wind speed	Passenger car: 200 km/h at 6 m² Van: 160 km/h at 8 m² Commercial vehicle: 120 km/h at 10 m²	Passenger car: 130 km/h at 6 m² Van: 100 km/h at 8 m² Commercial vehicle: 80 km/h at 10 m²
Roller dynamometer	2 axles (adjustable): 300 kW/axle from 35 km/h Max. drive power: > 250 kW from 35 km/h	2 axles (adjustable): 150 kW/axle from 30 km/h Max. drive power: > 100 kW
Temperature range	-30 to +50°C	-30 to +50°C
Humidity range	0°C dewpoint to 95% R.H.	0°C dewpoint to 95% R.H.
Solar equipment	350 to 1,200 W/m²	350 to 1,200 W/m²
Background noise	< 65 dB(A) at 50 km/h	< 70 dB(A) at 50 km/h
Temp. pre-conditioning area for cars and vans to externally heat coolant	-40 to +50°C	-40 to +50°C

Searching for the "sound of silence" in the acoustics lab
The acoustics lab in Stuttgart is one of Behr’s most important test facilities for developing new systems to improve the acoustic comfort of drivers and passengers. In the search for the “sound of silence”, developers are working on suppressing noise emissions from air conditioning and engine cooling as much as possible. The noise emissions of all components, modules, and complete systems are measured on the test bench, as well as inside the vehicle, in the acoustics lab.Our acoustics lab has echoic and anechoic measurement rooms to minimize ambient noise.

Using modern technology to suppress noise
We use various development tools to reduce the noise emission of our HVAC units and cooling modules. We simulate the air flows through the components and modules and then calculate the structural dynamic properties and determine the acoustic transmission functions.

Our artificial sensory head measurement technology absorbs the noise emissions corresponding to an actual person’s acoustic perception. We then evaluate the subjective noise perception in our acoustics studio with our customers and development partners.

In the acoustics studio, we also generate synthetic sounds which we then compare to subjective tests. We can measure all noise emissions and vibrations, i.e. the whole range of human acoustic perception, using this equipment. The design and construction of the air conditioning and engine cooling systems are then modified based on these measurements and analyses.