The aerospace industry is in a period of rapid change: established aircraft manufacturers are trying new ideas to maximize fuel efficiency, while new entrants are pioneering revolutionary concepts in electric flight and urban air mobility. These developments are affecting all areas of aircraft design, but one in particular needs special attention: noise.
Community noise – the noise levels experienced by people living and working near flight paths – has been controversial for decades, and governments have put limits on acceptable noise around airports. Up to now, aircraft manufacturers have met this challenge through the usage of acoustic absorber layers inside the engine nacelle, acoustic liners. However, ultra-high bypass engines are in development, which are getting larger in diameter and shorter in length and are being mounted closer to the wing. All of this results in lower liner efficiency and higher jet installation noise effects at a time when noise limits are getting lower.
Community noise is an even bigger problem for new electric vertical take-off and landing (eVTOL) urban air mobility concepts. These have to operate in densely populated areas much closer to buildings than conventional aircraft, and noise will make-or-break the concept of eVTOL. Compared to helicopters, eVTOL vehicles tend to produce higher-frequency noise due to their smaller rotors, making their noise more annoying. The idea of re-using existing heliports, many of which have been dismissed because of their acoustic impact, relies on the capability of eVTOLs to operate in a significantly quieter way than helicopters, and this constitutes a real challenge for designers.
Simulation is helping engineers to meet noise regulations and airlines to get community acceptance. In aircraft design, simulation can compare different design concepts and bridge the gap between the lab and the real world. New acoustic absorbing materials, such as the acoustic metamaterials being developed by the aerospace faculty of TU Delft, can reduce engine noise with small penalties in terms of aerodynamic efficiency.
The applications of simulation are wider than just aircraft design, however: trajectory has an impact on noise too, and with simulation, operation planners can find a flight path that minimizes community noise. To be even more specific, the design of eVTOL should integrate in a closer loop the vehicle design and the design of optimal procedures. This is possible by reducing the gap between system engineering and high-fidelity simulation approaches, and the respective user teams. The 3DEXPERIENCE Platform by Dassault Systèmes provides the ideal environment in which this methodological transformation can be actuated.
As eVTOL noise is sensitive to the flight procedure, the design and location of vertiports and other infrastructure can also be analyzed to study their impact on the surrounding area.
SIMULIA PowerFLOW is a fast and accurate tool for aerodynamic and aeroacoustic simulation. But just as important is the fact it is easy to use. Aircraft community noise needs complex analysis that traditionally needed years of experience to learn, and start-ups especially don’t have access to that knowledge. I see it as our social responsibility to properly pass this knowledge on to the next generation of engineers who are used to working in digital environments and may overlook some implications of the digital transformation.
Using PowerFLOW, we’ve developed specialized apps for aircraft community noise analysis which automate simulation set-up and post-processing. Users don’t need to know the detail of how to create a volume mesh, for instance, but can focus on actually studying the aircraft noise. The advanced workflow leads users through the post-processing without needing a Ph.D., and 3D visualization shows clearly the actual physical interactions that cause noise. I like to think of SIMULIA PowerFLOW also as a vehicle of knowledge, which you learn from as you use it.
If this has interested you in aircraft community noise simulation, I will be hosting an online interactive workshop on aircraft and rotorcraft noise. We will have presenters from within SIMULIA demonstrating the solutions for eVTOL and engine noise, as well as a guest presenter from TU Delft to talk about their metamaterial solutions.
The workshop will be held on September 29 2020, with two sessions for different time zones – one for Asia, Europe and Africa, and one for the Americas. More information and registration can be found here: https://events.3ds.com/interactive-workshop-on-aircraft-and-rotorcraft-noise-simulation
The workshop is part of a larger series entitled Achieving Quieter Flight Through Simulation. This three-part series discusses simulation for eVTOL as well as traditional aircraft and rotocraft designs. More information can be found here.
I hope to see you there!
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