Explore the cutting-edge capabilities of Ansys Fluent in the realm of aeroacoustics, revolutionizing how industries tackle noise reduction and improve sound quality.
Understanding Aeroacoustics
Aeroacoustics is a branch of acoustics that deals with the generation of noise by turbulent fluid motion and the propagation of these sounds through the fluid medium, such as air. This field is crucial in engineering because noise pollution can impact human health, environmental quality, and product performance. Engineers use aeroacoustics studies to design quieter aircraft, reduce noise in automotive design, improve the acoustics of HVAC systems, and in many other applications where controlling the sound generated by airflow is important.
The importance of aeroacoustics extends beyond comfort and environmental concerns; it also plays a significant role in compliance with regulations and standards. By understanding the fundamentals of sound generation and propagation, engineers can create designs that minimize acoustic footprints, leading to products that are not only more pleasant to the human ear but also more competitive in the marketplace.
What is Sound?
Sound is a "pressure disturbance" that the human ear can hear! Sound pressure refers to the local pressure variation from the ambient atmospheric pressure caused by a sound wave. When a sound wave travels through a medium like air, it causes compressions and rarefactions, leading to fluctuations in pressure. Sound pressure differs from the static pressure, as the latter one refers the force exerted by a fluid on a surface or within a volume (Figure 1).
Figure 1. Static pressure versus sound pressure
The unit of the sound pressure level (spl) is dB, and for different common sounds the variation in spl is shown in Figure 2.
Figure 2. The sound pressure levels for some common sounds
The spl -frequency chart indicates the characteristics of the sound with the tonal noise, corresponding harmonics, and broadband noise (Figure 3). For an engineer, this is a useful tool to have a better understanding on how and where the sound is generated, and thus can be reduced!
Figure 3. Characteristics of a sound wave in terms of sound pressure level and frequency
Key Features of Ansys Fluent for Aeroacoustics Simulations
Ansys Fluent is a powerful computational fluid dynamics (CFD) software widely used for aeroacoustics simulations. It provides a comprehensive suite of tools to model and analyze fluid flow and acoustic phenomena. Key features of Ansys Fluent include advanced turbulence modeling capabilities, a range of acoustic models such as the Lighthill's analogy, FW-H (Ffowcs Williams-Hawkings) equations, and Broadband Noise Source models. Additionally, Fluent's user-friendly interface allows for efficient setup of complex simulations and the ability to handle unsteady flows and transient noise predictions.
Ansys Fluent also integrates seamlessly with other Ansys tools, enabling multi-physics simulations that can capture the interaction between aerodynamics, acoustics, and structural mechanics. This holistic approach is essential for accurately predicting the noise characteristics of complex systems and designing effective noise reduction strategies.
Application
A sample application would be an aerodynamic and aeroacoustics simulation of a propeller. The propeller will rotate at 3770 rpm speed, and a microphone will collect the acoustic signals to provide the characteristic sound wave profile. The acoustic simulation will follow the steady CFD simulation. (Figure 4)
Figure 4. Sample application
The details of the subject, and Ansys Fluent aeroacoustics simulation can be found in the below video:
You can view this video on YouTube at this link: https://www.youtube.com/watch?v=flkFjI9N-_g