Stephane Caro

• PhD
• Vibroacoustics (wave6) at Dassault Systèmes

The external air low speed flow over a flat plate passed a half cylinder shape is computed using an unsteady CFD technique; the turbulent surface pressure field is analyzed in details; a frequency-wavenumber decomposition is used to identify the convective and acoustic energy concentration. A comparison is then made with results obtained using seve...

This paper presents two concurrent simulation strategies suited to compute the noise induced by external aerodynamic flows inside of vehicles. A typical applied problem would be the noise in a car induced by the flow around a side mirror. The traditional approach relies on a compressible, transient CFD computation. The result of such a computation...

Computational AeroAcoustics, or CAA, covers the development of innovative numerical methods for the simulation of the propagation of acoustic waves in three-dimensional regions characterized by non-uniform mean flows around bodies with complex geometries. Such methods are necessary to describe the nearfield radiation of aircraft individual noise so...

This paper reports on the validation of a hybrid computational aeroacoustics (CAA) method on a benchmark of a simplified HVAC duct. An acoustic analogy is adopted and an in-house unstructured flow solver is coupled to the ACTRAN commercial finite element solver. Two acoustic analogies are compared: the Lighthill and the Möhring analogies. The sensi...

This contribution reports on investigations to validate a computational aeroacoustics methodology. An acoustic analogy is adopted in which the Cenaero flow solver Argo is coupled to the commercial acoustic solver Actran/LA that uses a variational formulation of the Lighthill analogy. Two approaches to transfer noise sources from the uid dynamics me...

This paper presents different techniques to compute broadband noise at nacelle exhaust using the finite element code Actran/TM and the discontinuous Galerkin method code Actran/DGM. Actran/DGM is a dedicated tool for predicting the acoustic field at nacelle exhaust. This code allows modelling the acoustic propagation in treated nacelle in the prese...

This paper is the continuation of the work started last year by the consortium of the German car manufacturers Audi, BMW, Daimler, Porsche and Volkswagen that has presented the paper titled Numerical and Experimental Investigations of the Noise Generated by a Flap in a Simplified HVAC Duct. 1 In this paper, the first steps of an investigation carri...

This paper reports on the application of a computational methodology for the simulation of aeroacoustics problems. An acoustic analogy is adopted and a in-house three-dimensional unstructured flow solver is coupled to theommercial finite element solver that uses a variational formulation of the Lighthill analogy. Numerical investigations are perfor...

The most general approach to aeroacoustics consists in solving the compressible Navier-Stokes equations through a direct numerical simulation (DNS). However, because of the associated numerical cost, an alternative approach is required to solve engineering problems. One alternative approach consists in using an acoustic analogy, as first proposed b...

The difference of flow velocity between the free stream and the jet stream at a nacelle exhaust generates a shear layer where some hydrodynamic instabilities, called Kelvin-Helmholtz instabilities, can occur. Some instabilities occur in the shear layer in the computations with Actran/DGM a time domain code which solves the LEE equations (see,1,2 an...

This paper reports on the improvement and validation of a computational framework developed for the simulation of aeroacoustics problems. An acoustic analogy is adopted and a in-house three-dimensional unstructured flow solver is coupled to the Actran/LA commercial finite element solver that uses a variational formulation of the Lighthill analogy....

Following a recent paper1, new advances now allow reaching higher frequencies within a smaller amount of time. The Finite Element Code whose performance is benchmarked in this paper is a specific software package for solving propagation/radiation problems for turbo machinery noise.5 The code computes the propagation and "free field" radiation of gi...

The Council of European Aerospace Societies (CEAS) Aeroacoustics Specialists Committee (ASC) supports and promotes the interests of the scientific and industrial aeroacoustics community on a European scale and European aeronautics activities internationally. In this context, “aeroacoustics” encompasses all aerospace acoustics and related areas. Eac...

This paper describes an unusual application of a finite element code Actran, which was originally designed to simulate acoustic propagation in potential mean flows. The code is applied to the problem of duct mode radiation through an exhaust nozzle to the far-field; the effects of refraction across the jet shear layer are accounted for, this shear...

The purpose of this work is to evaluate a Computer Aided Engineering (CAE) method in which computational aero acoustics (CAA) techniques are used to predict the noise level from automotive fans. In this paper the extended version of the variational formulation of Lighthill's analogy is used. This formulation is ideally suited to the finite element...

Aero-Thermo-Mechanics department of ULB is currently developping a code based on a mixed Spectral/ Finite Elements discretisation offering a natural decomposition of a fully three-dimensionnal into a set of two-dimensional problems. The reduced simulation time compared to complete three-dimensional code offers new fields of investigation for the tu...

For being the major source of noise pollution in aero-engines, fan forward and rearward noise is of primary importance in the aeronautics industry. With a view to enabling acoustic-based design of engines’ nacelle and bypass ducts, Free Field Technologies has developed a tool, calledActran/TM, over the past fiveyears. Briefly, Actran/TM computes th...

In this paper, we investigate the use of the variational formulation of Lighthill's anal- ogy, implemented in a Finite/Infinite Element framework. We present an innovative way to handle porous boundaries (or equivalently, control surfaces upon which aerodynamic sources are defined). We show how Lighthill's analogy can be used to predict broadband b...

The flow through an HVAC blower fan, typical to the automotive industry, was solved using STAR-CD. Time varying pressure data was then exported to ACTRAN/TM where the CFD results were decomposed into acoustic duct modes, using a multiple plane matching method. These duct modes were then propagated to far field locations and compared with experiment...

Une part importante du bruit à large bande rayonné par les surfaces portantes (profils d’ailes ou pales de ventilateurs) provient de la dispersion , sous la forme d’ondes acoustiques, des perturbations de l’écoulement convectées au voisinage du bord de fuite. Les perturbations en question peuvent correspondre à de la turbulence ou à des instabilité...

Le calcul du bruit d'interaction des sillages du rotor avec les aubes du stator est une étape essentielle dans l'évaluation du bruit d'un système de ventilation complet. Dans ce type de problèmes, la principale difficulté vient de l'évaluation des sources. Pour obtenir un résultat probant, la technique la plus naturelle est de mener une simulation...

In this paper, a technique to compute the noise radiated by a large truck engine is presented. This technique is of particular interest at Volvo Powertrain, where the design process should be robust, fast, reliable, and involve the least possible human interventions. It will be shown that the technique proposed here fulfills most needs. The computa...