Noise mitigation is central to vehicle safety, comfort, and compliance – which is why engineers must find and control noise from

every possible source. Complex airflows, detailed geometry, and thermal transients all impact sound, so costly prototype testing alone

can’t help engineers find and mitigate unwanted noise throughout all of a vehicle’s systems. But design-driven simulationwith Exa is different. See the sound, identify its source, and evaluate design improvements to correct it – while

balancing noise targets with other, competing vehicle requirements – all before a single prototype is built.

Aeroacoustics Applications

HVAC SystemBalance climate control and noise targets to deliver total comfort.

Exhaust SystemVisualize complex airflow

to better control soundUnderbody WindSimulate detailed geometry of complex components to reduce wind noise.

Cooling FanManage engine temperature while controlling flow-induced noise.

Greenhouse WindReduce interior noise to improve customer experience.

Sunroof / Window BuffetingSimulate to eliminate this top consumer complaint.

Community / PasserbyMeet government and industry regulations.

Exa’s PowerACOUSTICS and PowerFLOWAccurately predict the turbulent airflow driven by complex geometry while capturing and propagating the noise inside and outside vehicle systems. Proven and acknowledged Lattice Bolzmann solver offers extensively validated accuracy in predicting aerodynamically-induced noise. It is transient, compressible, and offers very low numerical dissipation with the ability to handle complex, detailed geometry.

ONLY SIMULATION-DRIVEN DESIGN WITH EXA:- Offers proprietary turbulence and near wall models

- Computes noise sources using the dynamics of flow structures

- Includes under and upper bodies to evaluate radiated noiselevels and insertion losses to assess installed conditions

- Measures the effect of absorbing materials in the presence ofthe flow with Exa’s Acoustic Porous Medium (APM) solution

FIND: Flow-Induced Noise Detection by ExaExa provides diagnostic technology to pinpoint, rank, and quantify noise sources produced by air flow. Engineers can listen to sound generated by digital simulations before a prototype is ever built. Quickly investigate the performance of different system designs and architectures in order to achieve the right sound signature and meet noise and fuel economy standards with fewer design and prototyping iterations.

ONLY EXA’S FIND MODULE:- Provides 3-D maps of noise sources for easy visual analysis

- Simplifies the traditional analysis of the data using unsteadyflow and band-filtered animations or dB maps.

- Enables the automatic creation of clusters of noise sources

- Offers the user clear insight on the location and strength ofthe various noise-generating regions present in the system

Digital simulation with Exa applies real-world conditions to 3D geometry using a computational, physics-based approach to faithfully re-create and evaluate the mechanisms of flow-induced noise from cooling fans, like:

- Complex rotating and stationary geometry and tonal noise,including blade passing frequency

- Rotor casing interactions, stalling, and unsteady flow fields

- Broadband noise, vortex shedding, flow detachment, turbu-lent boundary layer noise, and tip vortex noise

- Installationeffects, which can influence inlet flow conditions

- Radiation of small amplitude pressure fluctuations

Seeing Sound with Exa

EVALUATING AND REDUCING FAN NOISELow-speed rotating axial and radial fans help manage engine temperature for commercial vehicles and heavy equipment by ensuring adequate airflow through heat exchangers, especially at low vehicle speeds or idle. But the community noise they generate is heavily regulated, which means failure to meet acoustic targets can lead to launch delays or expensive countermeasures to ensure

compliance. Cooling fan noise is also a perceived quality issue that can affect brand image and customer satisfaction. Physical testing is often a poor indicator of performance and can’t easily identify noise sources.

Simulation-driven design with Exa

lets leading firms hear greenhouse

wind noise long before production.

Visualize key noise sources resulting

from airflow, like these surface

pressure fluctuations.

Predict sound transmission to the

interior from all noise sources, like

acoustic loads on these panels.

Color and rank noise sources - here,

the side-view mirror - to quickly

target and evaluate design changes.

noise until late in the development process when high quality verification prototypes are built. But this may happen too late to efficiently resolve noise problems. Fixes at this late stage mean design re-work, additional sound packages, or acoustic glass at-tenuation—all expensive and time-consuming solutions. Reduc-ing associated costs and development time requires a reliable digital simulation method that can be used early in design and often throughout the program life cycle.

THE POWER OF DIGITAL SIMULATION:REDUCING GREENHOUSE WIND NOISE Reducing vehicle interior noise levels helps manufacturers im-prove driver and passenger comfort. With wind noise a dominant noise source during highway driving, impacting consumer loyalty and sales, significant engineering time and product costs are invested in meeting interior noise targets to remain competitive. Automotive OEMs are often unable to assess wind-related interior

also may result in degraded performance, driving late-stage de-sign changes. Exa’s solution for HVAC system noise can faithfully simulate the thermal transients, flow-induced noise, and complex details of the HVAC system, including true rotating geometry, to predict acoustic noise propagation throughout the HVAC system.

Simulation with Exa helps you:

- Predict noise sources

- Assess alternate designs

- Evaluate tradeoffs betweentargets

CONTROLLING HVAC SYSTEM NOISEThe HVAC system is complex, consisting of a blower and mixing unit, multiple ducts through which air is transported, and defrost solutions. The blower must supply sufficient pressure to achieve the right air flow rates for each thermal comfort setting. It is ex-tremely difficult to control the noise, which may be sourced from blower rotation or from the turbulent airflow moving through the mixing unit, the twists and turns of the ducts, and the registers. Compromises between airflow, thermal, and acoustic performance can result in late-stage design changes or degraded passenger comfort. The effects of integrating the HVAC system into the vehicle, which changes its performance relative to the test bench,