A review of flow acoustic effects on a commercial automotive exhaust system - methods and materials

Mohamad, Barhm

doi:10.30464/jmee.2019.3.2.149

Cited by 6 publications

(3 citation statements)

References 20 publications

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“…In this section, the effect of the positions of the muffler inlet and outlet on its acoustic performance is investigated. 19 The initial boundary conditions for the analysis of the muffler acoustic performance using COMSOL software are set as follows: (1) the airflow velocity expression of the muffler inlet is set to M a * c 0 ; (2) the type of inlet pressure acoustic field is set to "plane wave" and the pressure amplitude is set to 1 Pa; (3) the muffler outlet is set to a full sound absorption without reflection boundary; (4) the inner wall of the expansion chamber is set to a non-slip adiabatic boundary; (5) set The sound power at the inlet and outlet of the muffler are extracted respectively, and then calculated according to Eq. ( 12) to obtain the transmission loss curves of four types of singlechamber mufflers under no-flow conditions, as shown in Fig.…”

Section: Analysis In the Sound Fieldmentioning

confidence: 99%

Research on Suppression of Airflow Secondary Noise in a Muffler Based on Large Eddy Simulation

Zhao¹,

Li²

2022

The International Journal of Acoustics and Vibration

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Based on the Large Eddy Simulation (LES), the problem of the performance of a muffler being weakened by the airflow secondary noise in the expansion chamber was analyzed. Based on the different relative positions of the inlet and outlet, a single-chamber muffler is divided into four structures and a numerical simulation model of the flow field is developed. The LES was used to analyze the flow field and secondary noise in the expansion chamber. First, the LES is used to calculate the unsteady flow in the expansion chamber to obtain the turbulent intensity and the pressure pulsation distribution of the flow in the muffler chamber. Subsequently, a simulation model of the acoustic field was built separately to obtain the secondary noise distribution of the flow in the muffler by computing the flow field information. It is shown that the secondary noise properties in the muffler are related to its geometrical configuration. The turbulence intensity of the flow field in the chamber can be reduced by changing the airflow pattern in the chamber, to weaken the intensity of the airflow secondary noise. Finally, a structural modification of the two-chamber muffler was performed based on the findings of the study, and the improved muffler performance was evaluated through numerical simulations and field tests. Experimental results show that the improved muffler has better acoustic properties and increases the noise reduction capacity by about 18 percent. It further confirms that the intensity of secondary noise can be substantially suppressed by changing the internal structure of the muffler, which opens up new ideas for the future design and modification of exhaust mufflers.

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Section: Analysis In the Sound Fieldmentioning

confidence: 99%

Research on Suppression of Airflow Secondary Noise in a Muffler Based on Large Eddy Simulation

Zhao¹,

Li²

2022

The International Journal of Acoustics and Vibration

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“…In [20], Bowden studied experimentally the TL of muffler exhaust systems for maritime diesel engines based on a test bench. Mohamad developed a review concerning the methods and materials for AEM based on an analysis of the effects of internal flow for engines with internal combustion using CFD [21]. Babu et al optimized a hybrid muffler through the prediction of TL based on FEM models in ANSYS [22].…”

Section: Introductionmentioning

confidence: 99%

Recent Developments in Using a Modified Transfer Matrix Method for an Automotive Exhaust Muffler Design Based on Computation Fluid Dynamics in 3D

Bugaru,

Vasile

2024

Computation

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The present work aims to investigate the newly modified transfer matrix method (MTMM) to predict an automotive exhaust muffler’s transmission loss (AEMTL). The MTMM is a mixed method between a 3D-CFD (Computation Fluid Dynamics in 3D), namely AVL FIRETM M Engine (process-safe 3D-CFD Simulations of Internal Combustions Engines), and the classic TMM for the exhaust muffler. For all the continuous and discontinuous sections of the exhaust muffler, the Mach number of the cross-section, the temperature, and the type of discontinuity of the exhaust gas flow were taken into consideration to evaluate the specific elements of the acoustic quadrupole that define the MTMM coupled with AVL FIRETM M Engine for one given muffler exhaust. Also, the perforations of intermediary ducts were considered in the new MTMM (AVL FIRETM M Engine linked with TMM) to predict the TL (transmission loss) of an automotive exhaust muffler with three expansion chambers. The results obtained for the TL in the frequency range 0.1-4 kHz agree with the experimental results published in the literature. The TMM was improved by adding the AVL FIRETM M Engine as a valuable tool in designing the automotive exhaust muffler (AEM).

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“…The transmission loss has been optimized for new muffler design; other literatures played a significant role in validate their results. Mohamad [6] studied several new techniques through that literature review; the latest development has been done on exhaust systems with regard to acoustic performance. The basic theory behind both approaches is explained as well as a source characterization technique that can be used to link the two methods.…”

Section: Introductionmentioning

confidence: 99%

A hybrid method technique for design and optimization of Formula race car exhaust muffler

Mohamad

Jalics

Zelentsov

et al. 2020

International Review of Applied Sciences and Engineering

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In this work a multilevel Computational Fluid Dynamics (CFD) analysis has been applied for the design of a Formula race car exhaust muffler with improved characteristics of sound pressure level (SPL) 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 3D tools. Modern mufflers typically have a complex system of chambers and flow paths. There are a variety of sound damping and absorbing mechanisms working to quiet the sound flowing through a muffler and piping system. Two calculation methods were selected for this study. The muffler has a complex inner structure containing perforated pipe and fiber material. Computer-aided design (CAD) file of the muffler was established for developing Finite Element Analysis (FEA) model in AVL BOOST v2017 and another commercial advanced design software (SolidWorks 2017). FEA model was made to monitor the flow properties, pressure and velocity. After the model was verified, sensitivity studies of design parameters were performed to optimize the SPL of the muffler. The software analysis results are included in the paper. Recommendations are made for obtaining smoother SPL curves for various measurement methods.

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A review of flow acoustic effects on a commercial automotive exhaust system - methods and materials

Cited by 6 publications

References 20 publications

Research on Suppression of Airflow Secondary Noise in a Muffler Based on Large Eddy Simulation

Research on Suppression of Airflow Secondary Noise in a Muffler Based on Large Eddy Simulation

Recent Developments in Using a Modified Transfer Matrix Method for an Automotive Exhaust Muffler Design Based on Computation Fluid Dynamics in 3D

A hybrid method technique for design and optimization of Formula race car exhaust muffler

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