PhD Studentship: Silent Owl Flight Noise Generation by Turbulent Flows over Flexible Aerofoil Trailing Edge

Project details:

Noise pollution is a growing environmental issue and has become the second-largest environmental cause of health problems in Europe, just after air pollution. Among the environmental noise sources, aerofoil noise is one of the major contributors, including noise from aircraft wing, aeroengine fan and wind turbines. Therefore, it is crucial to effectively reduce them for a quiet living environment.

In nature, the owl is one of the birds that can fly almost silently. Its wings have several features that help to reduce the noise, such as feather fringe and comb [1]. Among them, elasticity is identified to play a key role in reducing noise. Theoretical modelling has shown the noise generation by scattering turbulent fluctuations at an elastic trailing ledge, which can change the scaling from 5 to 7 regarding velocity [2]. This indicates low noise emission at a low Mach number compared to a rigid trailing edge. However, the elasticity effect on hydrodynamics, how the turbulent boundary layer will be affected by the elastic trailing edge before being scattered acoustically, has not been fully known. This could subsequentially affect the acoustic scattering and could also potentially be affected by the generated noise, establishing a feedback loop by these flow-acoustics interactions.

In this study, we will extend our high-fidelity aeroacoustics simulation framework [3] to further model the elastic airfoil trailing edge and study the interactions of flexible trailing edge with both hydrodynamics and acoustics. The simulation results will be analyzed and compared with analytical models, then informing a refined acoustic model taking both into account with data-driven approaches. This research is inherently multidisciplinary, lying at the interface of fluid and solid mechanics, acoustics, and computing science. It will potentially improve our current understanding of the silent flight of owls by uncovering the full mechanisms of noise reduction by flexible trailing edge and eventually inspire the innovative design of quiet airfoils by tuning the elasticity of trailing edge.

Requirements:

The candidate will have a 1st class undergraduate or Master’s degree (or equivalent) in Physics, Mathematics, Mechanical or Aerospace Engineering, Computer Science or a related discipline. You should be highly motivated, and would be able to work independently as well as collaborate with others with effective written/oral communication skills. Knowledge of fluid mechanics or CFD is essential. Experience in programming (Fortran/C++/Python) and knowledge of acoustics and solid mechanics would be desirable.

How to apply:

The application must be made through the university’s online application system [3]. Please provide a cover letter summarizing your research interests and suitability for the position, the contacts of two referees and a curriculum vitae. Please send a copy directly to Dr Zhong-Nan Wang (z.n.wang@bham.ac.uk).

Funding details:

The PhD project is expected to start in September 2025. The successful applicant will receive an annual tax-free stipend of £15,514 per year and payment of home tuition fee up to 3.5 years. Additional funding can also be available for attending training events/workshop and academic conferences when necessary. The successful applicant will be able to work within a vibrant and multidisciplinary aerospace team under the College of Engineering and Physical Sciences at the University of Birmingham and also have opportunities to engage with the researchers at Southampton, Cambridge and Melbourne.

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