Methods for Efficient SimulationS of Aircraft Engine Noise
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- Mode-Matching in Engine Ducts with Vortical Flows
- Impedance Models in Time Domain including the Extended Helmholtz Resonator Model
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The MESSIAEN project focuses on the development of the ACTRAN/DGM software product for the simulation of noise generated by turbomachines found in aircraft and, thereafter, on the design of devices effecting a reduction of that critical noise source. To enlarge the scope of the project while maintaining the focus on a unified set of methods and tools, MESSIAEN investigated three distinct problems:
- aero-engines with an eye on the specific needs and challenges of the engine manufacturer (Rolls-Royce), the nacelle manufacturer (Aermacchi) and the aircraft manufacturer (Airbus) responsible for the integration of the nacelle-engine ensemble in the aircraft;
- helicopter engines (Turbomeca);
- air conditioning pack noise (LTS).
MESSIAEN tackles tonal (as opposed to broadband) sources of noise because the relevant theoretical models have reached a sufficient level of maturity to support industrial processes at the end of the MESSIAEN project. MESSIAEN focused on the solution of linearized Euler equations by a discontinuous Galerkin method (DGM) on unstructured grids. This method, modelling the near field of the source, is coupled with the Ffowcs-Williams and Hawkings integral method to predict the far-field acoustic pressure. Besides the development of the solver itself, the following topics have been addressed:
- Use of parallel processing techniques for tackling real industrial challenges, i.e., three-dimensional configurations over a representative frequency range in a CPU time compatible with industrial constraints.
- Non-reflecting boundary conditions were used to minimize the acoustic waves reflected when disturbances leave the computational domain.
- Stability issues of the Linearized Euler equations in the presence of strong shear have been assessed.
- Effective modelling techniques for including impedance boundary conditions (liners) in time-domain solution schemes were developed.
- Techniques for extracting aero-acoustic source terms from CFD results were enhanced.
The work of MESSIAEN continues within the TURNEX project.