Acoustic Characterization of Automotive Mufflers - Part I: Test Rig Design and Evaluation of Acoustic Properties

Ferrara, Giovanni; Ferrari, Lorenzo; Vichi, Giovanni; Lenzi, Giulio; Biliotti, Davide

doi:10.4271/2012-01-0800

Cited by 10 publications

(8 citation statements)

References 15 publications

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“…The underlying idea is to exploit simplified approaches (1D and quasi-3D) for DOE practice and to confine the usage of fully 3D simulations to perform the final validation where possible optimization of details is required. Despite the use of the above mentioned numerical approaches has proved to be predictive in case of simplified configurations [3,14,16], in the present work the numerical simulations are further validated by experimental measurements performed on real configurations by means of a dedicated acoustic test rig [17]. This comparison made possible to point out the quality of agreement that can be achieved by numerical approaches with real configurations.…”

Section: Introductionmentioning

confidence: 89%

“…Downstream to the second measurement section an acoustic termination sets acoustic boundary condition. The experimental measurements evaluate the acoustic pressure fields at the inlet and outlet of the air-box; the acoustic pressure waves are divided into incident and reflected components [17]. The measurement technique adopted to evaluate such waves on the two sides of the air-box is the multi-microphone technique [18].…”

Section: Experimental Analysismentioning

confidence: 99%

See 1 more Smart Citation

Fluid Dynamic and Acoustic Optimization Methodology of a Motorbike Intake Airbox Using Multilevel Numerical CFD Models and Experimental Validation Tests

Montenegro¹,

Torre²,

Cerri³

et al. 2013

SAE Int. J. Engines

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In this work a multilevel CFD analysis have been applied for the design of an intake air-box with improved characteristics of noise reduction and fluid dynamic response. The approaches developed and applied for the optimization process range from the 1D to fully 3D CFD simulation, exploring hybrid approaches based on the integration of a 1D model with quasi-3D and 3D tools. In particular, the quasi-3D strategy is exploited to investigate several configurations, tailoring the best trade-off between noise abatement at frequencies below 1000 Hz and optimization of engine performances.Once the best configuration has been defined, the 1D-3D approach has been adopted to confirm the prediction carried out by means of the simplified approach, studying also the impact of the new configuration on the engine performances. The calculations have been further validated by an extensive experimental campaign carried out not only on the test bench for engine performance analysis but also on an acoustic test bench developed by the University of Florence. The experimental acoustic characterization is based on the Multi-Microphone Technique, which guarantees a wider reliable frequency range of analysis and lower errors in the evaluation of the acoustic properties of the examined devices (such as mufflers or intake lines, etc.).Results of the calculations on both the baseline and optimized configurations have been compared to the measured acoustic performance carried with null flow conditions showing an encouraging agreement.

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Section: Introductionmentioning

confidence: 89%

Section: Experimental Analysismentioning

confidence: 99%

Fluid Dynamic and Acoustic Optimization Methodology of a Motorbike Intake Airbox Using Multilevel Numerical CFD Models and Experimental Validation Tests

Montenegro¹,

Torre²,

Cerri³

et al. 2013

SAE Int. J. Engines

Self Cite

View full text Add to dashboard Cite

show abstract

“…While all these theoretical tools are fundamental to the analysis and optimization of the acoustic response of ATS, their validity is highly dependent on the availability of reliable experimental data. In the literature, there is a wide variety of techniques for measuring the acoustic behaviour of dissipative systems [21]. These techniques range from techniques with external sound level meters [22] to techniques using multiple sensors in the ducts [23].…”

Section: Introductionmentioning

confidence: 99%

“…These techniques range from techniques with external sound level meters [22] to techniques using multiple sensors in the ducts [23]. In this last approach, it is possible to find methods with different degrees of complexity, from those that use two sensors located at the inlet and outlet of the element to be analysed [24], to those that use multiple sensors at the inlet and outlet and allow systems to be characterized with greater complexity, both at the structural level and regarding flow conditions [21].…”

Section: Introductionmentioning

confidence: 99%

On the Applicability of Cold Acoustic Measurements to High-Amplitude Hot Pulsating Flows

et al. 2022

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The experimental characterization of the acoustic characteristics of engine exhaust devices is usually carried out through measurements in cold conditions, due to the intrinsic difficulties associated with proper temperature control in an acoustic rig. While those measurements may be sufficiently indicative for the cold end of the exhaust (the silencing elements) their significance for the hot end (the aftertreatment system) is more doubtful, as a result of the high temperatures and, eventually, the higher amplitude of pressure waves acting on the system. In this paper, a direct assessment is provided on the significance of acoustic measurements in cold conditions for representing the actual behaviour of an aftertreatment system in a hot pulsating, engine-like flow. Making use of wave decomposition techniques, the measured characterization was convoluted with the hot-flow excitation and the device responses were directly compared. The results indicate that, while it is not possible to fully reproduce the behaviour observed in hot pulsating flow, the tendencies are reproduced, at least qualitatively. In particular, the effect of soot loading is fairly reproduced.

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“…Otherwise, PF modelling requires specific tools capable of predicting its operation under different unsteady flow conditions and with different PM loading. In the literature, there is a wide variety of experimental techniques that can be use to measure the acoustic behaviour of after-treatment systems [69]. These techniques range from those with external sound level meters [70] to techniques using multiple sensors in the ducts [71], typically condenser (pressure) microphones.…”

Section: Historical Evolution Of Studies In Atfertreatment Systemsmentioning

confidence: 99%

Acoustic and fluid-dynamic characterization of state-of-the-art exhaust after-treatment systems.

Navarro¹

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Continuously tightening pollutant and noise emission regulations have been the key motivation for engine -and engine related technology-research, development and optimization. Such trend gave rise to the gradual introduction of after-treatment systems to reduce pollutant emissions in automotive applications. However, in the last two decades the level of restrictions have made the use of after-treatment systems intensive and mandatory, evolving from small individual devices to very complex systems often including more than one device.Even though the main purpose of after-treatment systems is pollutant emissions abatement, they also exert a strong influence on wave dynamics, back-pressure and acoustic behaviour of the exhaust line, therefore changing the flow, acoustic and pressure characteristics of the exhaust flow. This in turn redefines the boundary conditions for the main silencing device (muffler) placed downstream. A better understanding of the sound attenuation and pressure drop due to the presence of after-treatment systems could have beneficial impacts, allowing the optimized design of the devices and the complete exhaust lines, especially the muffler. It was considered that a promising approach to reach a better understanding on the matter would be to account for the influence that usual components and characteristics of after-treatment systems have on their actual behaviour.Experimental and modelling approaches were used to study and characterize the acoustic and fluid-dynamic behavior of a diverse set of state-of-the-art after-treatment systems and devices, covering a wide range of elements and characteristics representative of after-treatment applications of commercial use. Transmission loss and pressure drop were selected as the key parameters to account for the sound attenuation and back-pressure generated by each device. Well established measurement facilities and procedures were used for the experimental characterization. In parallel, 1D, 3D CFD and even coupled 1D-3D simulation approaches on the basis of the "virtual twinning" concept were implemented on commercial software, aiming to replicate the experimental results in order to provide additional information and help deepen the understanding of internal phenomena, three-dimensional flow and acoustic effects. i Funding Acknowledgements This research has been funded by the Programa de Ayudas de Investigación y Desarrollo PAID-01-19, from Universitat Politècnica de València (UPV), which granted my pre-doctoral contract. xvi "Investigar es ver lo que todo el mundo ha visto, y pensar lo que nadie más ha pensado". "Research is to see what everybody else has seen, and to think what nobody else has thought". -Albert Szent-Györgyi xvii * Pressure drop measurements in the cold flow test bench. * Transmission loss measurements in the impulse test rig.

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Acoustic Characterization of Automotive Mufflers - Part I: Test Rig Design and Evaluation of Acoustic Properties

Cited by 10 publications

References 15 publications

Fluid Dynamic and Acoustic Optimization Methodology of a Motorbike Intake Airbox Using Multilevel Numerical CFD Models and Experimental Validation Tests

Fluid Dynamic and Acoustic Optimization Methodology of a Motorbike Intake Airbox Using Multilevel Numerical CFD Models and Experimental Validation Tests

On the Applicability of Cold Acoustic Measurements to High-Amplitude Hot Pulsating Flows

Acoustic and fluid-dynamic characterization of state-of-the-art exhaust after-treatment systems.

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