Aeroacoustic sound sources, which result from turbulence of airflow around objects, can be a significant source of noise. When designing aerodynamic shapes, it is important to pay attention to details. This includes:

  • choosing the right contours
  • using smooth surfaces
  • avoiding unnecessary edges that could disrupt air flow

Once the shapes are carefully designed, air resistance can be minimized, allowing vehicles to move more efficiently. That results in better fuel economy and a reduction of areodynamic noise.

Our Acoustic Cameras are valuable tools when combined with wind tunnel testing in various industries, including automotive design, aerospace engineering, and wind turbine development. By integrating an Acoustic Camera into a wind tunnel setup, product developers such as vehicle manufacturers can effectively study and analyze the acoustic characteristics of aerodynamic models or components. Noise sources can then be precisely identified and engineers can develop solutions to minimize them.

The combination of customized array design, high channel counts and various optimized algorithms guarantee the best possible results for acoustic imaging in wind tunnels. Our advanced system is engineered to deliver the highest precision, ensuring accurate and detailed acoustic imaging in real time. Since time is a crucial factor in wind tunnel testing, we guarantee the fastest possible data transmission and processing.

Aerodynamic Testing

In the automotive industry, ensuring comfort for drivers and passengers is crucial, even at high speeds. One important aspect is the optimization of various vehicle components such as exterior mirrors, spoilers, antennas, A-pillars, or other cavities to minimize wind-induced noise. To meet this challenge head-on, we offer the microphone array EVO AC Pro or customized arrays according to your need, specifically engineered for exceptional performance in wind tunnel applications.

Setup of a Wind Tunnel

In a typical wind tunnel testing setup, our microphone array configuration consists of three to five arrays strategically positioned. One array is centered above the object being tested, while the other two arrays are placed on the left and right sides. Additionally it is possible to add one microphone array above the front of the test object and one array under it. There is the option to place a spherical array inside the vehicle's interior. This configuration allows simultaneous synchronous acquisition of all noise sources, extensive data collection, and precise analysis of wind-related noise.

Powerful Software Tools

To facilitate the exchange and analysis of measurement results from wind tunnel tests, we have developed the software NoiseImage Conclusion. NI Conclusion provides an intuitive user interface for easy result overview, allowing for direct comparison of multiple variants through acoustic maps or spatially averaged spectra. It also enables seamless export of results for integration into other workflows. Additionally, the software offers a wide range of settings and customization options to meet individual requirements. The NoiseImage Wind Tunnel module contains all wind tunnel-specific algorithms as a basis for your analysis of the acquired data in the wind tunnel.

Correlation Analysis for Localization of Sound Sources

In addition, our advanced software NoiseImage is capable of performing correlation analysis. This analysis allows you to distinguish between different sound sources and specifically identify those that have a direct impact on the driver or occupants. By pinpointing the critical noise sources on the acoustic map, you can prioritize effective noise reduction strategies and optimize the overall acoustic experience within the vehicle.

How the Amiet Correction Helps with Acoustic Signals.

In wind tunnels, the airflow creates an effect known as the shear layer. The shear layer changes the travel times between sound sources and microphones causing distortions in the acoustic map that affect the accurate localization of sound sources. To address this issue, shear layer correction, often referred to as Amiet correction, is essential. The wind tunnel module of our NoiseImage software corrects the measured acoustic data, ensuring that sound sources are accurately represented in their respective locations.

Wide Range of Software Functionalities

In addition to shear layer correction and correlation analysis, the NoiseImage system offers a range of additional features. For example, it takes into account the YAW angle, which simulates the vehicle's airflow from different directions. It also incorporates the Clean-SC decomposition algorithm, which separates sources within acoustic maps more distinctly. By combining the power beamforming algorithm with other advanced analysis techniques, our solution provides a comprehensive tool for investigating and optimizing the aeroacoustic properties of your products. Numerous algorithms have been validated through extensive collaboration with Volkswagen and the DLR (German Aerospace Center) in a major project.

This advanced NoiseImage wind tunnel module, along with the associated hardware, represents state-of-the-art technology in the field of aeroacoustics. These features enable researchers and engineers to gain a precise and reliable understanding of sound sources during wind tunnel tests.

Customized Wind Tunnel Solutions

The entire wind tunnel system is developed in-house. This means that both the hardware and the software can be individually adapted to your customer requirements. The state-of-the-art technology has proven itself in many applications and is continuously improved by our development department in cooperation with leading international aeroacousticians and the valuable feedback from our customers.