BMW opens new aeroacoustic and electric drive center

BMW has replaced its old wind tunnel at the Group’s Research and Innovation Center (FIZ) in Munich. The new Aeroacoustics and Electric Drive Center (AEC) is said to house a 100-meter wind tunnel, supposedly the largest vertical acoustic wind tunnel in the world and also the quietest.

The building consists of two halves: in addition to a multifunctional part with a workshop, testing and measurement equipment, and a prototype for high-voltage batteries and inverters, the AEC has a technically and structurally unique wind tunnel. With a length of just under 100 m, a height of 45 m, and a width of 25 m, it is the world’s largest vertical acoustic wind tunnel and the quietest.

The background noise level is 54.3 dB (A) at 140 kph, “which is as low as a quiet conversation or a quiet air conditioning system,” BMW emphasizes. The blower has a capacity of 4.5 MW, producing winds of up to 100,000 m3 of air per minute and speeds of up to 250 kph. Because of the wind tunnel’s size, it can be used to examine “even the largest and most powerful vehicles such as the Rolls-Royce Phantom or the BMW X7,” says the carmaker.

Aeroacoustics

The new wind tunnel enables “groundbreaking advances in aeroacoustics research.” The goal is to measure the noises caused by headwinds – and to make cars as quiet as possible, particularly the Neue Klasse. “Quiet is premium,” says Daniel Böttger, Head of Complete Vehicle Development at BMW AG. “Our focus is on meeting the premium standards of our vehicles. An important part of this is acoustics, particularly for quiet electric models.”

The wind tunnel also has another feature to help researchers test aeroacoustics: it is designed as “an acoustic semi-free-field space.” That means the wind tunnel has a sound-resistant floor and no sound reflections.

This is important because it “enables a realistic simulation of the situation on the road,” says BMW, adding, “The frequency range for semi-free-field conditions from 30 Hz is unique for a vehicle wind tunnel and covers the entire audible spectrum.”

Multi-use and flexibility

Other features include a 216-microphone acoustic camera that localizes background noises “with an accuracy of less than one centimeter” and a laser vibrometry system that measures mechanical vibrations. The tunnel can also “study wind and rolling noises,” separating the phenomena.

“In addition, various modules, such as a vehicle-accessible glass floor or a vehicle scale for motorcycles, can be replaced quickly without moving the vehicle. This allows developers to test different configurations quickly and efficiently,” BMW explains.

The second ‘semi-detached house’ of AEC is home to workshops, testing and measurement stands, and prototype lines. The focus is also on electric mobility. The experts from the BMW Group are building and testing prototypes of future high-voltage batteries for electric vehicles here; 15,000 m² are available on several floors.

On a further 800 m², inverters for future electric motors will be manufactured on a pilot line under clean room conditions. The inverter is a crucial component of an electric motor. Its task is to convert the direct current from the high-voltage battery into alternating current for use in the electric motor.

The spaces in AEC are designed to be ‘multifunctional’ and flexible in the long term. This means that the company will also be able to respond to various requirements in the future and rebuild the spaces quickly.