Exhaust System Evaluation and Design by Non-Linear Modeling

Sapsford, S. M.; Richards, Vanessa C.M.; Amlee, Duane R.; Morel, Tom; Chappell, Mary T.

doi:10.4271/920686

Cited by 19 publications

(13 citation statements)

References 2 publications

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“…Certainly this nonlinear gasdynamic approach is very promising for prediction of the acoustical behavior of silencers connected to the engine and the noise level radiated from the open terminations. Recently some interesting studies have been published about the nonlinear modeling of the various muffling elements of a typical engine silencer, [6][7][8][9][10] showing satisfactory and encouraging results that have demonstrated the validity of the nonlinear onedimensional approach. However, the simulation of typical, realistic engine mufflers is not a mature area yet, because of the complexity of the internal structures ͑including abrupt and gradual area changes, axial side-branches, orifices, flow reversals, perforated pipes, and sound-absorbing material͒.…”

Section: Introductionmentioning

confidence: 98%

Nonlinear fluid dynamic modeling of reactive silencers involving extended inlet/outlet and perforated ducts

Onorati

1997

noise cont engng j

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A numerical simulation model has been developed to predict the attenuation features of silencers in the frequency domain. The model is fully nonlinear, solving the conservation equations for one-dimensional, unsteady, compressible flow in duct systems. The numerical techniques adopted are the MacCormack and the Lax-Wendroff shock-capturing finite difference schemes, and the mesh method of characteristics. The numerical code is able to simulate the gasdynamic response of a muffling pipe system to a harmonic pressure perturbation, enabling the evaluation of the transfer function of the equivalent acoustic filter. The simulation has been extended to several silencers, resorting to appropriate boundary conditions and acoustically equivalent duct systems. Helmholtz resonators, expansion chambers with internal orifices, extended inlets and outlets, and other more complex silencing duct systems have been modeled, achieving a satisfactory agreement between predicted results and experimental data, measured in a semi-anechoic room. Furthermore, an investigation of perforated pipes has been carried out, following a detailed approach to model plane-wave propagation in the perforate and in the cavity liner. The method suggested takes into account every single hole with its diameter, length, and friction coefficient, allowing for the correct modeling of the reactive and dissipative behavior of the silencer. ©

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Section: Introductionmentioning

confidence: 98%

Nonlinear fluid dynamic modeling of reactive silencers involving extended inlet/outlet and perforated ducts

Onorati

1997

noise cont engng j

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“…This formulation arises naturally from the linearization of the finite volume approach as used in gas-dynamic simulations [23]. In [22] it was only checked that the results obtained with this approach were in good agreement with those obtained from a gas-dynamic finite-volume time domain simulation, but a detailed justification of the procedure and comparison with experiments and other computational methods were missing.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, from equations (3), (4), (21) and (22) one can write: (23) This can be conveniently written in matrix form as:…”

Section: Assembling Of the Three-dimensional Acoustic Networkmentioning

confidence: 99%

“…where U 0 is the mean flow velocity across the interface, which can be obtained from a time domain steady flow computation performed with the same spatial discretization, as described by Sapsford et al [23]. In summary, mass and momentum exchange between volumes may be represented by considering each volume as a multi-port, as defined by equation (3), and then connecting those multi-ports by means of 2-ports as defined by equation (8) or equation (9).…”

Section: Theorymentioning

confidence: 99%

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Analysis of acoustic networks including cavities by means of a linear finite volume method

Torregrosa

Broatch

Gil

et al. 2012

Journal of Sound and Vibration

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A procedure allowing for the analysis of complex acoustic networks, including three-dimensional cavities described in terms of zero-dimensional equivalent elements, is presented and validated. The procedure is based on the linearization of the finite volume method often used in gas-dynamics, which is translated into an acoustic network comprising multi-ports accounting for mass exchanges between the finite volumes, and equivalent 2-ports describing momentum exchange across the volume surfaces. The application of the concept to a one-dimensional case shows that it actually converges to the exact analytical solution when a sufficiently large number of volumes are considered. This has allowed the formulation of an objective criterion for the choice of a mesh providing results with a prefixed error up to a certain Helmholtz number, which has been generalized to three-dimensional cases. The procedure is then applied to simple but relevant three-dimensional geometries in the absence of a mean flow, showing good agreement with experimental and other computational results.

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“…Such methods have become standard in commercial codes, either as the core solver [29,30], or used locally for elements exhibiting significant three-dimensional features, such as plenums and mufflers [31]. Typically, when these methods are applied to simple duct junctions, a single volume is used for the junction with appropriate effective areas and characteristic lengths at each connection with the adjacent ducts.…”

Section: Introductionmentioning

confidence: 99%

A Study of the Transient Response of Duct Junctions: Measurements and Gas-Dynamic Modeling with a Staggered Mesh Finite Volume Approach

et al. 2017

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Duct junctions play a major role in the operation and design of most piping systems. The objective of this paper is to establish the potential of a staggered mesh finite volume model as a way to improve the description of the effect of simple duct junctions on an otherwise one-dimensional flow system, such as the intake or exhaust of an internal combustion engine. Specific experiments have been performed in which different junctions have been characterized as a multi-port, and that have provided precise and reliable results on the propagation of pressure pulses across junctions. The results obtained have been compared to simulations performed with a staggered mesh finite volume method with different flux limiters and different meshes and, as a reference, have also been compared with the results of a more conventional pressure loss-based model. The results indicate that the staggered mesh finite volume model provides a closer description of wave dynamics, even if further work is needed to establish the optimal calculation settings.

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Exhaust System Evaluation and Design by Non-Linear Modeling

Cited by 19 publications

References 2 publications

Nonlinear fluid dynamic modeling of reactive silencers involving extended inlet/outlet and perforated ducts

Nonlinear fluid dynamic modeling of reactive silencers involving extended inlet/outlet and perforated ducts

Analysis of acoustic networks including cavities by means of a linear finite volume method

A Study of the Transient Response of Duct Junctions: Measurements and Gas-Dynamic Modeling with a Staggered Mesh Finite Volume Approach

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