Actran

Overview

Free Field Technologies develops and supports the Actran family of acoustic CAE products. The company proudly serves customers as diverse as car manufacturers and their suppliers, civil and military aircraft and aircraft engine manufacturers, loudspeakers and other audio device producers, consultants, universities and research centres.

Free Field Technologies also provides related services: acoustic CAE consultancy (on-site or off-site), training, specific developments, contract research and provides a range of services in the field of acoustic design. Free Field Technologies is also involved in multiple research programs in acoustics, aero-acoustics, vibro-acoustics, high-performance computing etc.

Actran Acoustics

Actran Acoustics is the foundation module of the Actran family and is both a standalone tool and a pre-requisite for advanced modules like Actran VibroAcoustics, Actran AeroAcoustics or Actran TM.

Actran Acoustics contains a wide set of acoustic modeling features making it the CAE tool of choice for simulating a large variety of problems, from the simplest component to the most elaborate system. The Actran Acoustics product relies on exclusive powerful, robust, fast and reliable acoustic finite and infinite element library.

Sound fields in cavities are easily analyzed with Actran Acoustics, which offers both modal and physical approaches. Absorbing walls may be modelled in detail using impedance conditions or porous material models.

Actran Acoustics is also uniquely suited for sound radiation analysis where it brings unprecedented efficiency, speed and productivity to your analysis process. Actran Acoustics features seamless interfaces with most FEA structural analysis codes like Nastran.

Actran Acoustics also offers powerful features for analyzing sound propagation in ducts and may be used for designing, e.g. intake and exhaust lines or air distribution systems in buildings, aircrafts and cars.

Among the many advanced features available in Actran Acoustics are the handling of a mean flow field (convected acoustic propagation) and temperature gradient effects. Specific elements are also available to handle visco-thermal effects important when sound waves propagates in narrow ducts or thin cavities (e.g. hearing aids, solar array panels, etc.).

Target Applications:

• Sound radiation by vibrating structures: powertrain, engine components (oilpan, intake manifold and air filter, valve cover, etc.), compressors, electrical motors, loudspeakers and more.
• Intake and exhaust noise, including complex mufflers and silencers.
• Air conditioning units and distribution systems (calculation of transfer matrices coefficients).
• Sound absorption inside passenger compartment of cars, trains and aircrafts.
• Sound propagation in complex media with mean flow or temperature gradient.
• Audio devices such as telephones, hearing aids or musical instruments.

Actran For Nastran

Combine the strength of Actran and Nastran for advanced vibro-acoustic modeling

Actran is a powerful tool for modeling and analyzing complex vibro-acoustic systems and specifically trim components. Such components are usually made of materials with high damping and strong acoustic absorption characteristics; as such, they have a significant influence on the overall vibro-acoustic behavior of the structure.

Accounting for high damping very often relies on the use of physical coordinates, hence Actran models are usually available in physical coordinates.

Nastran is the reference tool for vibro-acoustic analysis of lightly damped structures and cavities. It features efficient modal analysis solution sequences, making it suitable for handling large models like automotive vehicle body-in-white or an aircraft fuselage.

Nastran models are usually available in modal coordinates.

Actran for Nastran provides CAE engineers advanced features for mixing the best of both worlds: Actran physical model and Nastran modal model.

Three types of combined models may be created:

• Actran for Nastran is able to merge a set of Actran models of individual trim components with a Nastran body-in-white model in order to create a fully trimmed body vibro-acoustic model.
• An Actran model may be set in its real-life working environment by connecting it to an existing Nastran model (e.g. a detailed Actran model of a layered windshield may be connected to a Nastran model of the vehicle body).
• A Nastran model may be enriched by including a reduced Actran model of a specific component. The Actran component is defined as a DMIG data block in the Nastran deck.
• Actran for Nastran makes the vibro-acoustic analysis of fully trimmed bodies possible. To model the problem with both efficiency and accuracy, innovative hybrid methods are used. With these hybrid methods, the strength of modal and physical approaches are combined and their weaknesses circumvented.

Target Applications:

• Acoustic transmission through components in real-life mounting conditions
• Trimmed body modeling using a combination of Actran detailed models in physical coordinates and a Nastran body-in-white modal model

Actran VibroAcoustics

A complete, robust, reliable, productive and high performing vibro-acoustic CAE module

Actran VibroAcoustics is the most complete vibro-acoustic simulation software currently available on the market.

Built on top of Actran Acoustics and relying on powerful finite and infinite element library, Actran VibroAcoustics provides a rich library of elements, materials, boundary conditions, solution schemes and solvers and is used by the most demanding engineers, researchers and teachers to solve challenging vibro-acoustics design problems.

To build the structural model in Actran you can rely on its rich material library. Indeed, Actran features not only conventional materials for acoustic or visco-elastic media but also more specific models for porous or incompressible media, composite materials or active components (including piezo-electric ceramics). All material types can be combined in a single model to achieve the most realistic results.

A modal basis may also be imported from most structural FEA codes and be used as a representation of the structural model.

Your vibro-acoustic model may be submitted to the most realistic working conditions by combining acoustic, dynamic and kinematic boundary conditions, as well as more physical excitations like diffuse sound field and turbulent boundary layer.

Actran AeroAcoustics and VibroAcoustics can be combined: modeling complex aero-vibro-acoustics problems has now become reality!

The available solution schemes include coupled or uncoupled models in physical and modal coordinates, in frequency or time domain. The very efficient linear equation solvers and the parallel processing capabilities make Actran the solution of choice for solving industrial-size problems in design optimization processes.

Target Applications:

• Automotive: noise related problems from powertrains, intakes, exhausts, passenger compartment, trim, seats, hoses, tires, windows and windshields, audio, HVAC.
• Aerospace: sound transmission through cockpit and fuselage, noise propagation in air distribution system, response to TBL excitation, random dynamic response of rocket payload at take-off.
• Consumer goods: telephones, headsets, loudspeakers, hearing aid devices, disk drives, washing machines, refrigerators, cameras.
• Defense: underwater acoustics, sonars.

Actran AeroAcoustics

Predicting the noise generated by complex flows

Actran AeroAcoustics is a finite element based acoustic solver for predicting the noise generated by turbulent flows. Actran AeroAcoustics recovers aerodynamic noise sources from flow simulations performed with commercial CFD codes such as Fluent™, Star-CD™, StarCCM+™ or Powerflow™. The complete simulation procedure involves three steps:

• An unsteady flow simulation is performed by the CFD code. At each time step, the CFD solution (velocity, density and pressure fields) is stored in its own native format or in the Ensight™ format.
• Actran AeroAcoustics computes the aero-acoustic noise sources from the CFD results produced in step 1. This involves translating results from the time to the frequency domain and interpolating them from the CFD to the acoustic mesh. Maps of the aero-acoustic sources produced at this stage are in themselves useful results which can be used to identify the most effective sources.
• The radiated acoustic field radiated is then computed. This produces a wide set of relevant results: acoustic pressure, velocity or intensity maps, frequency response functions of various local (pressure) or global (power) quantities.

This multi-step strategy offers several advantages:

• (1) Each part of the work can be done independently by different engineers, departments or even companies with different responsibilities or skills.
• (2) A single CFD simulation can feed different acoustic simulations (e.g. with different acoustic treatments).
• (3) The acoustic mesh does not need to be refined where the aerodynamic structures are small (for instance in the boundary layers).

Actran AeroAcoustics offers high performance solvers and parallel processing features and is fully integrated in Actran VI.

Actran AeroAcoustics can be combined with Actran VibroAcoustics in order to address aero-vibro-acoustic challenges.

Target applications:

• Air conditioning modules (HVAC).
• Side mirror noise.
• Airframe noise (landing gear, trailing edge).
• Air distribution systems.

Actran TM

Actran TM is the reference CAE tool for analyzing the sound radiated by turbo machines and for optimizing the related acoustic treatments. Actran TM is used extensively by many leading aerospace companies that rely on the tools' accuracy, ease-of-use and performance for reaching their strategic acoustic design goals.

Actran TM contains all advanced modeling features required for turbo machinery noise analysis. To capture the important convection and refraction effects, the sound waves propagate on top of a non-uniform background mean flow which can be calculated by Actran or imported from a CFD simulation. The influence of the mean flow on the performance of acoustic liners is accounted for thanks to the Myers boundary condition. The acoustic source is defined in terms of incident duct modes of arbitrary order and their amplitude can be defined in a variety of ways (e.g. normalized amplitude, intensity, equal distribution of energy on all propagating modes) or derived from pressure fluctuations calculated on a set of planes by one of the supported CFD tools. Both 3D and axisymmetric models can be defined.

One of the challenges of acoustic CAE is to handle large models associated to high wave number and to large geometrical size and complexity. Actran TM meets this challenge thanks to its efficient solver technology that includes advanced parallel processing.

Actran TM is used not only for optimal aircraft engine nacelle liner design but also on inlet and outlet liners for helicopter turbines, environmental control systems (ECS) or auxiliary power unit (APU). Actran TM is also used for non aerospace applications like computer cooling system noise and more.

Aero-Acoustic Simulation of a HVAC Duct from MSC Software Corporation on Vimeo.

Actran TM can be complemented by Actran DGM to solve problems involving complex shear layers and flow gradients occurring at the engine exhaust.

Target Applications:

• Aircraft engine noise, including nacelle design
• Ducted cooling systems (electronic devices)
• Blower systems (air conditioning modules)
• Helicopter turbine noise

Actran DGM

Modeling noise propagation in complex flows using linearized Euler equations and discontinuous Galerkin methods

Actran DGM solves the linearized Euler equations using discontinuous finite elements and is used for predicting the noise propagation in complex physical conditions. It is particularly well suited to solving aero-acoustic problems at the exhaust of a double flux aero-engine, including effects such as propagation through strong shear layers, high temperature gradients and non-homentropic mean flows. Actran DGM can address 2D, 2.5D (axisymmetric with azimuthal order) or 3D problems. It includes all required boundary conditions: decomposition of the engine excitation in duct modes, non-reflective boundary conditions with absorbing buffer zones; liners are modeled using a time-domain translation of the Myers BC (Extended Helmholtz Resonator Model).

The straightforward mesh generation is one of the key advantages of Actran DGM. As an unstructured mesh method, it is not submitted to the standard constraints of a Finite Difference mesh. As the order of the elements is automatically adapted, the mesh can be "non-homogeneous" (i.e. using very small and large elements in the same model) without any performance degradation. In addition, the same mesh can be reused for frequencies of ratio 1 to 4 (i.e. a mesh that was designed to run at a frequency of 1000Hz can be used for frequencies ranging from 500Hz to 2000Hz).

Thanks to the implementation of a discontinuous spatial scheme for solving the Linearized Euler Equations, the performance is highly scalable in parallel. This scalability of the RAM consumption and computational time makes the solution of very large problems possible.

Target Applications:

• Exhaust of turbomachines
• Inlet of large turbomachines
• All acoustic propagation problems with non-homogeneous mean flow conditions

Actran VI

Actran's powerful and user-friendly pre- and post-processor

Actran VI is the new graphical user interface specifically designed for pre- and post-processing vibro- and aero-acoustic analyses of all Actran modules.

Including an Actran input file reader to check or modify input files generated by other tools, Actran VI supports several mesh formats (Nastran BDF, ANSYS RST and CDB, Actran DAT and NFF, I-DEAS UNV, Patran Neutral Format) as input for creating Actran input files.

Its various integrated pre-processing tools ease the creation and editing of Actran models. It is easy to visualize specific Actran model features (such as modal basis, sources or infinite elements coordinate system), to specify the projection parameters between incompatible meshes, to insert additional entities (e.g. control points) or to visualize the specified boundary conditions. Additionally, it is also possible to define analysis templates (with or without mesh) to ease the creation of recurrent analyses.

The post-processing tool supports different results formats, such as OP2, UNV, NFF, RST, HDF and punch files. It contains different visualization modules, such as contour plots (maps), iso-surfaces, vectors or deformations, which can be freely combined and controlled using different filters. Synchronized viewports makes it easy to compare results at different frequencies, phases, times or related to different load case.

An animation module dedicated to complex harmonic results coupled with video export capabilities is also included.

Actran VI includes the PLTViewer and WaterfallViewer modules for easily displaying and handling frequency response functions, in single or multiple loadcases.

Target Applications:

• Validation, visualization and modification of existing Actran analyses.
• Creation of new Actran analyses.
• Display of all Actran results.