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  • New Advances of Acoustic Simulation Technologies for Aero / Defense IndustriesZe Zhou

    FFT / MSC

  • Free Field Technologies

    Founded in 1998, joined MSC Software in 2011

    Headquartered in Brussels, Belgium

    Activities:

    Development of the Actran software

    Services support, training, consulting & technology transfer

    Research in acoustic CAE and related fields

    More than 300 industrial customers worldwide

  • Actran Across Industries

  • Themes of Acoustic / AeroAcoustic Simulation

    Trends in (Aero)Acoustic Simulation:

    Boundary elements , Finite elements Discontinuous Galerkin (DG)

    method

    Larger problems, higher frequencies

    Higher Mach numbers

    better sources generation, better acoustic propagation !

  • The Actran Software Suite

    Actran Acoustics

    Actran Vibro-Acoustics Actran Aero-Acoustics Actran TM

    Actran for Trimmed body DMPActran SNGR

    ActranVI

    Actran DGM

  • From Actran FEM to Actran DGM

    Actran DGM solves the Linearized Euler Equations LEE (including the energy equation)

    Non-uniform and Rotational mean flow can be addressed

    Non Isothermal mean flow are take into account

    Acoustic Pressure, velocity and density are independently resolved

    Navier-Stokes equations

    EULER

    viscous shear stress

    thermal conductionare ignored

    Actran DGM

    Actran FWH / FEM ( potential flow)

    Irrotational flow

    Isentropic flow

    5 Unknowns per node (Velocity, pressure & density)

    Frequency DomainTime Domain

    Rotational flow

  • Actran DGM (Discontinuous Galerkin Method)

    Actran DGM Solving LEE

    Time domain solver, results in frequency domain

    as well

    High order elements: 1- 16

    Automatic elements order selection and time stepselection

    Features:

    Propagation in rotational flow, boundary layer flowand supersonic flow

    Massive scale problem / high freq problems

    Highly scalable and GPU acceleration

    Sketch of location of degrees of freedom. Dofs are duplicated at the element inte

    rface.

  • History of the Exhaust Noise at Airbus

    Actran DGM is used at Airbus since 6 years in R&D context

    It solves the Linearized Euler Equations (LEE) in time domain.

    It computes acoustic propagation through rotational steady mean flow

    2D axisymmetric simulation3D simulation CROR Near-field Noise

    FFT acoustic conference 2014, Simulation of installation effects of aircraft engine rearward fan noise with Actran/DGM, J-Y. Suratteau

    Time

  • Airbus - Installation Effects of Aircraft Rear Fan Noise

    Challenge

    Simulations of large scale domains including flow effects such as the acoustic radiation from turbofan engine installed on the aircraft.

    MSC Solutions

    Actran DGM is used for computing the far fieldnoise taking account of shapes of engine, wingand pylon. The acoustic propagation accounts for the mean flow computed by steady RANS simulations.

    Value

    Good correlation with measurements on a canonical test-case (gaps of 1dB). Actran DGM shows a very good computational efficiency and can be used in an industrial context.

    AIAA Conference, Simulation of Installation Effects of Aircraft Engine Rear Fan Noise with ACTRAN/DGM, A. Mosson, D. Binet, J. Caprile

    Main acoustic phenomena to simulate

    pressure real part mode (13,1)

    RANS Flow around the engine Model: engine, pylon, part of the wing

    Installation effect (wing effect) above the wing (0H) and below the wing (6H)

  • Actran DGM for APU Noise at Ground ICAO Regulation for Ramp Noise

    Actran DGM for noise @ ground with a realistic APU exhaust mounted on a A30X Aircraft

    Numerical Model :

    8500 m3

    1000 Hz

    22 CPU hours on 64 procsJet at APU exhaust

    Ground/Fuselage InteractionICAO Norm

    SPL at microphones

    * Aircraft geometry inspired by A30X AIRBUS single aisle aircraft project

  • Actran DGM Support of Supersonic Flows

    What: Acoustic propagation in flows with M>1 in Actran DGM

    Targets:

    Exhaust of turbo-engines

    Acoustic propagation in supersonic jets

    Supersonic vehicles (e.g. aircrafts, space launchers)

    Key Benefits:

    More accurate physics representation

    New applications fully addressed

    Exhaust propagation from space launcher travelling at M=1.5

  • Actran DGM GPU Acceleration

    Typical Application in aero-engine: Exhaust noise propagation

    130M DOFs

    Low memory (6GB) and GPU acceleration

  • AeroAcoustic Source Generation: Acoustic Analogies

    13

  • Lighthill Analogy

    14

  • Lighthill Analogy & Mohring Analogy

    15

  • Actran DGM with Thompson boundary condition

    What: Support of the integration mapping

    method for Thompson BC

    Targets: Propeller noise, Open Rotors noise

    Key Benefits: Time and model complexity

    reduction due to coarser DGM elements and bigger time step

    CROR acoustic propagation Image curtesy of Airbus

  • Actran DGM :Thompson Boundary Surface for Sources

    In Actran DGM:

    The Thompson boundary condition allows to provide realistic solutions at the boundary and at the same time provides a non-reflected behavior

    Requires velocity, density and pressure on a surface at each time step of an unsteady CFD

    Linearized Euler Equation

    Variational formulation of the Linearized Euler Equation

    The Thompson boundary condition feed the surface contribution

  • Roadmap of Further Developments for Actran DGM

    Aeroacoustics volume sources (Lighthill

    Analogy) in Actran DGM will be available in

    2017

    18

    DGM

    FEM

  • SNGR: Stochastic Noise Generation and Radiation

    What: Stochastic Noise Generation and Radiation (SNGR) delivers acoustic results based on inexpensive RANS CFD simulation

    Targets: Aero-acoustic applications where unsteady CFD can be computationally expensive (e.g. wind noise, landing gear, side-mirrors, HVACducts)

    Key Benefits: Computational time reduction for synthetic source computation

    Acoustic

    Sources

    Acoustic Radiation

    Unsteady CFD

    Engineering Timeline

    Actran

    SNGR

    Actran SNGR & DMP

    Steady RANS

    CFD

    Acoustic Radiation

    StandardCAA

    SNGRSNGR4 DMP

    CFD 345 10 10Actran 5 50 12.5Total 350 60 22.5

  • Introduction to Actran SNGR

    SNGR Principles Based on RANS input

    Synthesize turbulent velocity fields used for the CAA Lighthill sources computation

    RANS

    Mean flow

    Turbulent statistics

    Tu

    rbu

    lent S

    pe

    ctr

    um

    )(kE

    Random number

    generatorV

    on K

    arm

    an -

    Pa

    oU

    ser

    Def

    ined

    ExperimentalLES based

    or

  • SNGR: HVAC Demo case

    Example : Computation of Deltas dB on HVAC configurations

    Test Case : Simple 90duct without and with flap

    Flow Inlet

    Flow Inlet

    Without Flap

    With Flap

    RANS (k-) DES

  • SNGR: HVAC Demo case

    Delta dB of the Average Pressure at Microphones Placed in Far Field :

    Performance Comparison (with flap model) :

    CFD : RANS : 2.5 MCells / DES : 4.5 Mcells (32 parallels)

    CAA : 980 KDOFs

    10 dB

    RANS Unsteady CFD Sources Acoustic

    RANS Actran SNGR Acoustic

    Actran Aeroacoustics

    Actran SNGR

    SNGR is 5.8 Times Faster for predicting relative levels!

  • Analytical Fan Noise Sources

    What: Dipole/Monopole-based blade noise model based on Amiet(1) and Dierker(2) models

    Target: Low speed fan noise applications

    Key Benefits:

    Analytical fan noise model (axial and centrifugal)

    Fast design of fan noise applications

    (1) R. K. Amiet, Acoustic radiation from an airfoil in a turbulent stream, JSV, 1975(2) Dierke, J., et al, Installation effects of a propeller mounted on a wing with Coanda flap. Part II. Atlanta, USA , 2014. 20th AIAA/CEAS. 3189

  • Non-Parametric Variability Method (NPVM)

    What: Non-deterministic approach in Modal Frequency Responses through a Monte-Carlo solution framework

    Targets: Aerospace & auto vibro-acoustic applications

    Key Benefits: Extension of Actran capabilities in the mid-frequency

    range Access to the dispersion of vibro-acoustic responses

    BEGIN PARAMETERNUMBER_SAMPLES 20

    END PARAMETER

    BEGIN COMPONENT 1MODAL_ELASTICDOMAIN Structured_mesh1MODES_FORMAT OP2FIRST_MODE_INDEX 0NON_PARAMETRIC_VARIABILITY_STIFFNESS 0.05NON_PARAMETRIC_VARIABILITY_MASS 0.05NON_PARAMETRIC_VARIABILITY_DAMPING 0.05

    END COMPONENT 1

    NPVM implementationCh. Soize, A nonparametric model of random uncertainties for reduced matrix models in structural dynamics, Probabilistic Engineering Mechanics, 15, 2000

  • Step 2 Energy distribution in different patchesStep 1 Automatic Model Patch partitioning

    Energy Analysis

    What: Energetic post-processing of large/high frequency structural models

    Targets: Automotive and aerospace structural applications

    Key Benefits:

    Finite-element-based energetic analysis

    Handling of results on a patch level when local results are less relevant (e.g. on large models and/or at high frequencies)

  • Adaptivity capabilities Overview

    What: Adaptive meshing technology (H-Adaptivity) to: Structural surface elements; Equivalent fluids / porous components

    Key Benefit: Important reductio

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