Predicting the noise generated by complex flows

Whether noise comes from an air conditioning system, a rotating fan, or any other device that creates noise through turbulent flows, the sound generation and propagation mechanisms must be addressed to satisfy the ever increasing customer quality expectations. These systems are often required to operate for extended periods of time. Even low noise levels can significantly degrade the comfort for the user. With Actran, engineers from all industries have tools to predict and understand how to design quiet workplaces, quiet car and aircraft interiors, or silent electronic devices.

Actran AeroAcoustics is a module that features advanced capabilities to predict accurate and efficient noise generation of turbulent flows. Results from an unsteady flow simulation performed with CFD codes such as MSC’s SC/Tetra™, Fluent™, Star-CD™, StarCCM+™, Powerflow™, OpenFOAM™ and others are used by Actran AeroAcoustics to compute aerodynamic noise sources. The acoustic propagation from these aerodynamic sources are then computed to provide users with acoustic results such as noise levels and directivity.

Using Actran AeroAcoustics, the noise generated by any turbulent flow can be thoroughly predicted. Users can benefit from all features of the Actran software suite to study the interaction between the aeroacoustic noise sources and a vibrating structure, absorbent materials, or acoustic traps such as resonators.

Applications for Actran AeroAcoustics include rotating fans, air conditioning modules and side mirrors. It provides users with a complete understanding of the physical phenomena involved in the noise creation process.

Actran AeroAcoustics offers high performance solvers and parallel processing features with full integration in the Actran pre- and post-processing environment, Actran VI. It can also be combined with Actran VibroAcoustics in order to address aero-vibro-acoustic challenges such as side mirror noise.

Predicting the noise generated by complex flows from steady CFD solutions

Use this module to predict the noise generated by turbulent flows from steady CFD solutions. Actran SNGR recovers aerodynamic noise sources from flow simulations performed with CFD codes such as Fluent™, Star-CD™, StarCCM+™, Powerflow™, SC/Tetra™ or OpenFOAM™. The results from an steady flow simulation obtained from a RANS CFD analysis are used from the Actran SNGR to synthesize the noise sources, These sources are then imported into an acoustic computation and are then propagated. Actran SNGR allows addressing the noise generated from turbulent flows in a much faster way than classic aero-acoustic approaches and it is specifically useful when relative levels between different designs are needed such as in optimization loops.

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

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

Sample applications:

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

A powerful acoustic CAE tool for turbomachinery noise prediction

Use Actran TM to analyze the sound radiated by turbomachinery and to optimize the related acoustic treatments. One of the challenges of acoustic CAE methods is handling of large models associated to high wave number and to large geometrical size and complexity. Actran TM provides efficient solver technologies to address this problem, which includes advanced parallel processing.

In addition to studying aircraft engines, Actran TM can be used to analyze inlet and outlet liners for helicopter turbines, environmental control systems, and auxiliary power units, and for non-aerospace applications like computer cooling systems. Actran TM can be complemented by Actran DGM to solve problems involving complex shear layers and flow gradients occurring at engine exhaust.

Sample Applications:

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

Advanced vibro-acoustic analysis combining Actran and MSC Nastran

Actran for Trimmed Body is a powerful tool for modeling and analyzing complex vibro-acoustic systems such as 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.

Actran for Trimmed Body 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 Trimmed Body 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.

Sample 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

Jet engine exhaust noise modeling

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 uses an unstructured mesh method, and is not constrained by standard limitations of Finite Difference Method. As the order of the elements is automatically adapted, the mesh can be non-homogeneous, with a combination of very small and large elements in the same mesh, without any performance degradation.

Sample Applications:

• Exhaust of turbomachines
• Inlet of large turbomachines

Dedicated pre and post-processor for the Actran CAE software family

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.

Sample Applications:

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