The Importance of Aeroacoustics in Electric Cars
As the automotive industry continues to shift towards electric vehicles with their near-silent drivetrains, the focus on noise generation from wind, tires, and vibration is becoming increasingly important, especially for premium manufacturers.
BMW has recently unveiled its new Aeroacoustics and Electric Drive Centre (AEC) in Munich, replacing its outdated acoustic wind tunnel. This state-of-the-art facility at the BMW Group Research and Innovation Centre is specifically designed to meet the demands of developing electric vehicle drivetrains.
The AEC comprises two main components. The first is a multifunctional space that includes workshops for prototype work and testing equipment. The second is an aeroacoustic wind tunnel, touted as the quietest and largest in the world, measuring 100m long, 45m high, and 25m wide.
Constructing a wind tunnel capable of accurately measuring the noise levels of already quiet electric cars presented several challenges. The buildings were built in a pit to isolate them from external noise and vibration, with a 3m-thick floor slab and sound-insulated facade.
The second building, likened to a “semi-detached house,” houses workshops, testing and measurement stands, and prototype assembly lines. Additionally, a cleanroom area is designated for manufacturing future inverters.
The main test chamber boasts a background noise level of 54.3dBA, equivalent to speaking in hushed tones or a quiet air-conditioning system. This low level of intrusive noise allows for precise measurement of headwind noise.
With the ability to generate wind speeds of up to 155mph, thanks to a 4.5MW blower, the wind tunnel moves 100,000 cubic meters of air per minute. The chamber is designed as an acoustic semi-free-field space, ensuring that none of the surfaces, apart from the floor, reflect sound.
