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Hybrid Approach for the Assessment of Paths in Pass by Manoeuver

Centro RIcerche Fiat S.C.p.A.-Domenico Amodeo
Centro Ricerche Fiat S.C.p.A.-Marco Danti, Massimo Biasiolo
  • Technical Paper
  • 2020-01-1550
To be published on 2020-06-03 by SAE International in United States
Current vehicle regulations demand for a challenging decrease in the overall exterior noise as a benefit for the health of citizens and road users. New limits have been implemented in UN R51.03 (based on ISO 362-1:2015) to reduce the emitted noise both at constant speed and in full load so as to cover most of the real urban driving conditions. In order to achieve those targets the carmakers have to refine the trim of their vehicle and an experimental approach can take place too late. This paper shows a method for the pass by noise simulation exploiting the numerical transfer functions and a library of experimentally characterized sources with the aim to reduce the noise and find out a better tradeoff between costs and effectiveness of the modifications. Moreover a simple software tool for the treatment of the data and to ease the workflow has been created and used for the rank assessment of the different paths.
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Numerical Investigation of Narrow-Band Noise Generation by Automotive Cooling Fans

Chalmers University of Technology-Omar Fares, Huadong Yao
Volvo Car Group-Chenyang Weng, Linus Zackrisson, Magnus Knutsson
  • Technical Paper
  • 2020-01-1513
To be published on 2020-06-03 by SAE International in United States
Axial cooling fans are commonly used in electric vehicles to cool batteries with high heating load. One drawback of the cooling fans is the high aeroacoustic noise level resulting from the fan blades and the obstacles facing the airflow. To create a comfortable cabin environment in the vehicle, and to reduce exterior noise emission, a low-noise installation design of the axial fan is required. The purpose of the project is to develop an efficient computational aeroacoustics (CAA) simulation process to assist the cooling-fan installation design. This paper reports the current progress of the development, where the narrow-band components of the fan noise is focused on. Two methods are used to compute the noise source. In the first method the source is computed from the flow field obtained using the unsteady Reynolds-averaged Navier-Stokes equations (unsteady RANS, or URANS) model. In the second method, the azimuthal modes of the flow field obtained using the steady RANS with the moving reference frame model are treated as the sound source. While the first method is able to resolve any…
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Comprehensive Automotive Active Sound Design

Siemens Digital Industries Software-Ricardo Sales
  • Technical Paper
  • 2020-01-1545
To be published on 2020-06-03 by SAE International in United States
In the past years Active Sound Design has found its entrance into the automotive field as an efficient means to add some sporty sound components to vehicles with combustion engines. But, nowadays, with the growing market share of hybrid and battery electric vehicles and the legal requirement to add artificial exterior sound with Acoustic Vehicle Alert Systems (AVAS), wider applications scenarios open-up, and new skills, processes and tools are required to define, generate and implement these new types of sounds. A huge advantage is that Active Sound technologies allow a stringent implementation of a Brand Sound for the OEMs. This stringent implementation requires a corresponding Brand Sound approach to define and role this concept out into various vehicle sounds, which will be presented. Today’s applications of Active Sound Design require a flexible and comprehensive generation of different sound types for combustion and electric powertrain driven vehicles, so that the corresponding toolchain must be flexible, easy to edit, and of specific suitability for automotive applications. A major prerequisite is that the generated sounds are authentic, even…
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Pass-by Noise Prediction of a Vehicle

CAE-NVH, Product Development, Royal Enfield, Chennai.-RajaGopal B., Santosh Gannu, Abhilash M, GS Krishnamurthy, Rod Giles
  • Technical Paper
  • 2019-32-0593
Published 2020-01-24 by Society of Automotive Engineers of Japan in Japan
The forthcoming pass-by noise regulations have impacted the automotive sector, which further leads to the reduction of noise in the vehicle. The prediction of pass-by noise at an early stage will reduce the overall cost as well as time for an automobile industry and helps to reduce the overall product development life cycle. This supports the design activities of a vehicle.Msc ACTRAN/NASTRAN/ADAMS and GT Suite are major tools used in the present study to develop a simulation method to mimic the predefined testing norms. In Actran interior and exterior noise propagation is performed. Interior noise flow obtained by compressible flow analysis which uses exhaust/intake line velocity/temperature as boundary condition. The exterior noise propagation obtained by direct frequency response using acoustic duct mode with unit pressure injected into the intake and exhaust system and compressible flow field map results as input, this will take care of both noise propagation. Similarly for engine exterior noise radiation done by Nastran unit frequency response analysis and later actual loads from multi-body dynamics multiplied with direct frequency response analysis in…
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Maximum Exterior Sound Level for Snowmobiles

Snowmobile Technical Committee
  • Ground Vehicle Standard
  • J192_202001
  • Current
Published 2020-01-15 by SAE International in United States
This SAE standard establishes the instrumentation, test site, and test procedure for determining the maximum exterior sound level for snowmobiles. Sound propagation is directly related to the ground cover and provides the largest variation to the measured result. A correction factor is introduced to improve year-round test repeatability of the results on grass surfaces by correcting their spectrum to be similar to snow-covered spectra. Measured sound pressure levels are also highly dependent on the degree of track slip present when performing the vehicle acceleration. Operators should attempt to limit track slip as much as possible while maintaining the requirements described in 5.1.1.
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A Computational Process to Effectively Design Seals for Improved Wind Noise Performance

SAE International Journal of Advances and Current Practices in Mobility

Dassault Systemes SIMULIA-Robert Powell, Sivapalan Senthooran, Philippe Moron
Jaguar Land Rover-Nicholas Oettle
  • Journal Article
  • 2019-01-1472
Published 2019-06-05 by SAE International in United States
The ability to assess noise transmitted through seals to cabin interiors early in the design process is very important for automotive manufacturers. When a seal design is inadequate, the noise transmitted can dominate the interior noise, making the wind noise performance of the vehicle unacceptable. This can cause launch delays, increasing costs and risking loss of sales. Designing seals using conventional experimental processes is challenging, since the location and strength of flow noise sources are not known when the seal design is planned. Making changes to the seal system after the tooling stage is expensive for manufacturers as tooling and redesign costs can be considerable. Deliberate overdesign by adding multiple layers of seals in a wide range of locations also can reduce profit by unnecessarily raising part and manufacturing costs. Consequently, there is a strong motivation to use reliable computational capabilities to predict interior noise transmitted through seals early in the design process to address these challenges, designing seals right first time.The current study presents a computational process that can be used to predict interior…
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Exterior Acoustics Using Infinite Elements

Altair Engineering-Anurag Rajagopal, Dilip Mandal, Junji Saiki, Ujwal Patnaik
Published 2019-06-05 by SAE International in United States
The idea of employing an infinite element to solve acoustic problems in an unbounded domain has demonstrated significant promise. Starting from first principles, the detailed element formulation for a mapped wave-envelope infinite element is presented. This, in conjunction with an efficient search algorithm to map receiver grid locations to the pertinent infinite element on the boundary, is used to enhance an established finite-element based vibro-acoustic solver for frequency response in order to solve large scale industrial problems. The solver is then subjected to a thorough validation and verification study using problems whose solutions are established either through classical texts or alternative approaches to demonstrate the accuracy, robustness and efficiency of the current solution.
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Influence of Rib Stiffener Design Parameters on the Noise Radiation of an Engine Block

SAE International Journal of Engines

Ford Otosan, Research and Development Center, Turkey-Çiğdem Karaca
Istanbul Technical University, Turkey-Ender Balcı, Ozgen Akalin
  • Journal Article
  • 03-12-02-0013
Published 2019-03-14 by SAE International in United States
Stiffener ribs are widely used to increase the stiffness of engine blocks, shifting the vibration modes to higher frequencies where excitation is weaker so that radiated noise can be reduced. The effect of different rib design parameters on the radiated noise emission of a diesel engine has been investigated considering its impact on block weight. A heavy-duty engine block was modeled using finite element method, multi-body dynamics approach was used to determine the excitation forces acting due to combustion pressure and inertias, and boundary element method was used to find the acoustic transfer vectors which give the relationship between engine surface velocities and sound pressure levels at predetermined microphone locations. Initially, the baseline analytical sound pressure level and surface velocity results for the engine without ribs were obtained. Two prototype engines, with and without stiffened ribs, were tested in an acoustic dynamometer in complete speed range. Then, the problem was narrowed down to a specific surface patch on the block at a critical engine speed. The effects of various ribbing design parameters have been identified…
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A Pass-By Noise Prediction Method Based on Source-Path-Receiver Approach Combining Simulation and Test Data

SAE International Journal of Advances and Current Practices in Mobility

ESI Group-Massimiliano Calloni, Chadwyck Musser, Abderrazak Mejdi, Augusto Medeiros
ESI North America-Alexis Castel
  • Journal Article
  • 2019-26-0188
Published 2019-01-09 by SAE International in United States
Optimizing noise control treatments in the early design phase is crucial to meet new strict regulations for exterior vehicle noise. Contribution analysis of the different sources to the exterior acoustic performance plays an important role in prioritizing design changes. A method to predict Pass-by noise performance of a car, based on source-path-receiver approach, combining data coming from simulation and experimental campaigns, is presented along with its validation. With this method the effect of trim and sound package on exterior noise can be predicted and optimized.
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Aero-Acoustics Noise Prediction of 3D Treaded Tyre Using CFD

ANSYS INDIA PVT LTD.-Bhanu Gupta
CEAT LTD.-Chirag Bharatbhai Patel, Sharad Goyal, Abhishek Saraswat
Published 2019-01-09 by SAE International in United States
Tyre exterior noise legislation (pass-by) is becoming more stringent with time. To cater to these requirements, it is very important to understand the tyre noise generation and enhancing mechanisms such as air pumping, air turbulence, pipe resonance, horn effect in high frequency region from 500Hz to 4000Hz. These phenomena are affected by air flow around and within the tyre pattern hence, CFD based approach is chosen for tyre exterior noise. The CFD based methodology helps in fine tuning the tread pattern to reduce aero acoustic noise level which leads to reduction in the product design cycle time. In present study, 3d transient CFD aero-acoustic modelling approach results were validated against the anechoic tyre rolling noise test data which captures the air-born noise mechanisms for frequency range of 1 kHz to 4 kHz.
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