Computational Aeroacoustics

This was the first one-day NAFEMS Seminar devoted to Computational Aeroacoustics and CAE methods for noise propagation and transmission, where Invited speakers from industry, academia and the leading software providers gave an insight into noise issues and computational tools applied to noise abatement in up-front design.

Many industry sectors are facing increasing pressure from customers to reduce flow noise and its transmission to the interior environment or propagated externally to by passers. CAE is proving to be an increasingly valuable tool to help understand the flow noise generation propagation and transmission mechanisms. Consequently, engineers are able to design against them either by reducing the source or minimising its propagation in the aerodynamic/hydrodynamic domain and transmission through structures.

In this seminar, our presenters covered all the principle methods for predicting aeroacoustic noise generation mechanisms; tonal and broadband, arising from rotating machinery, coherent flow structures and turbulence; from stochastic models to fully wall-resolved large-eddy simulation (LES).

The traditional methods for computational aeroacoustics were covered, including the use of aeroacoustic analogies up to the direct simulation of noise.

Case studies from the automotive, aerospace, marine, power generation and many more sectors illustrated the use of Computational Fluid Dynamics (CFD) in the time domain, and also frequency based modelling using Boundary Element Methods (BEM), Finite Element Methods (FEM) and Statistical Energy Analysis (SEA).

Presentations

pres_sandberg.pdf
Computational Aeroacoustics: Sources
- An overview of sources, direct versus hybrid approaches, DNS and cheaper ways of computing sources.
Richard Sandberg, Professor of Fluid Dynamics and Aeroacoustics, Aerodynamics and Flight Mechanics Group, University of Southampton
pres_boyle_1.pdf
Efficient Modeling of Flow-Induced Noise and Flow-Induced Vibrations
- Presentation of the most efficient methods to model aeroacoustic sources and capture the sound propagation and induced vibrations for stationary or rotating problems; surface versus volume distributed sources; tonal and broadband fan sources.
Mark Boyle,Product Manager Virtual.Lab Acoustics, LMSpres_kowalczyk.pdf
Model Scale Noise Measurements of Operating Propeller
- Noise measurements of operating propeller were carried out in cavitation tunnel. Good cavitation and hydroacoustic measurements are vital for validation of predictive methods. The challenges in CFD-based simulation ared iscussed.
Sebastian Kowalczyk, Head of Analyses Group, Ship Design and Research Centre, CTO, Polandpres_detandt_1.pdf
Solving Flow Noise Problems with Hybrid Methods
- A review of different flow noise problems and their FEM based solution, including noise propagation mechanisms in non-uniform flows, capture of aerodynamic turbulent noise sources and discussion on modelling of aerodynamic and acoustic excitations of a vibrating structure.
Yves Detandt, AeroacousticTechnolgies Manager, Free Field Technologies, MSC Software Company

pres_caridi.pdfSimulation Approaches for Modeling Airborne Noise
- An overview of direct Computational Aeroacoustics methodology, Far-field noise propagation using the Ffowcs Williams-Hawkings acoustics analogy, and broadband noise models. Special attention will be paid to Scaled Resolved Simulation turbulence models to obtain an accurate transient solution of an unsteady turbulent flow which is essential to high-fidelity acoustic predictions.
Domenico Caridi, Team Leader - European Technology Group, Ansys, Milan

On the Use of Full-Frequency Vibro-Acoustic Models for Wind Noise Predictions
- Describing a full-frequency vibro-acoustic approach that can be implemented into an industrial design process and combines FEM,FEM/SEA and SEA methods.
Denis Blanchet, Engineering Services Manager, Vibro-Acoustics, ESI Group

pres_mendonca_1.pdfCFD Methodologies including Large Eddy Simulation for Noise Prediction
- Presentation of the wide spectrum of methods available in commercial CFD software; from steady-state stochastic/correlation models, to fully transient resolution of the flow and acoustics features using compressible CFD and LES-based turbulence modelling.
Fred Mendonça, Director of Aeroacoustics, CD-adapcopres_toppinga.pdfNumerical Aeroacoustics at Daimler AG
- Overview of on going developments, detailed analysis of CFD solution sets, challenges and recent improvementsReinier Toppinga, Aerodynamics & Aeroacoustics, Mercedes-Benz Cars Development pres_gaylard.pdfAeroacoustic Simulation at Jaguar Land Rover
- A review of some of the experiences of developing and deploying aeroacoustic simulation at a premium automotive manufacturer.Exploring the capability of a Lattice Boltzmann code to deliver predictions of wall pressure fluctuations, their utility in the development process, integrating CFD with experiment and the prospects for the future.Adrian Gaylard, Technical Specialist for Aerodynamics, Jaguar Land Roverpres_coupland.pdfComputational Methods for Aero-Engine Noise Prediction
- An overview of the application of CFD and CAA methods to predict aero-engine tonal and broadband noise sources and the noise propagation to the far-field, including examples of low noise blade design and experimental validation.John Coupland, ISVR, University of Southampton (formerly of Rolls-Royce plc)pres_mendonca_2.pdfTowards Aero-Vibroacoustics for Internal Noise Transmission
- Case study of a generic side-view mirror for which experiments have been performed at ISVR, Southampton University. The CFD predictions are intended for validation of the flow mechanisms, and data analysis using temporal and spatial Fourier analysis aimed at understanding the separable excitations of the structure arising from the flow and acoustics.
Fred Mendonça, Director of Aeroacoustics, CD-adapcopres_petrone.pdfBroadband Noise Prediction of a Low Speed Axial Fan
- Some challenging application examples will be presented which will include low speed axial fan broadband noise prediction.For all cases comparison with experimental data will be shown.
Giovanni Petrone, Ansys, UK

Wind Noise Source Characterization and How it Can be Used to Predict Vehicle Interior Noise
- This presentation focuses on process implementation and presents results from very coarse to very detailed simulation models and compares these results with experimental results; using source term weighting, wavenumber transformations and combinations of several methods; such as CFD, FEM, BEM, FE/SEA Coupled and SEA.
Denis Blanchet, Engineering Services Manager, Vibro-Acoustics, ESI Group

pres_detandt_2.pdfUnderstanding Flow Noise Generation and Propagation Mechanisms of Side Mirror Noise in the Cavity of a Car
-Focus on side mirror noise and comparing the turbulent pressure fluctuations acting on the vibrating structure to the acoustic field generated from external side mirror noise sources and impacting the structure of the car. The comparison is addressed at the driver's position and considers the acoustic properties of the car cavity (carpets, seats, ...).
Yves Detandt, Aeroacoustic Technolgies Manager, Free Field Technologies, MSC Software Companypres_boyle_2.pdfTowards Improved Automotive Cabin Comfort: Application of the Aeroacoustic Analogy to HVAC Flow-Induced Noise and Side Window Flow-Induced Vibrations
- Case study highlighting how to improve cabin comfort by analyzing noise generated by turbulent flow in a generic HVAC system and noise transmitted through the flow-excited side windows.
Mark Boyle, Product Manager Virtual.Lab Acoustics, LMS

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