Flow Field Analysis and Improvement of Automobile Exhaust System Cold End

Hou, Xiaofan; Guo, Xiaohong; Liu, Zhien; Yan, Fuwu; Peng, Fuming

doi:10.1109/cise.2010.5676819

Cited by 4 publications

(7 citation statements)

References 1 publication

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“…Temperature variations within a silencer can reach, in some configurations, values around 200ºC [15] and more than 100ºC [16] in the axial and radial directions, respectively. As the temperature distribution can affect the acoustic behavior of the silencer considerably, several authors studied the influence of these gradients in the silencer transmission loss.…”

Section: Introductionmentioning

confidence: 99%

Point collocation scheme in silencers with temperature gradient and mean flow

Denia

Sánchez-Orgaz

Baeza

et al. 2016

Journal of Computational and Applied Mathematics

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This work presents a mathematical approach based on the point collocation technique to compute the transmission loss of perforated dissipative silencers with transversal temperature gradients and mean flow. Three-dimensional wave propagation is considered in silencer geometries with arbitrary, but axially uniform, cross section. To reduce the computational requirements of a full multidimensional finite element calculation, a method is developed combining axial and transversal solutions of the wave equation. First, the finite element method is employed in a two-dimensional problem to extract the eigenvalues and associated eigenvectors for the silencer cross section. Mean flow as well as transversal temperature gradients and the corresponding thermal-induced material heterogeneities are included in the model. In addition, an axially uniform temperature field is taken into account, its value being the inlet/outlet average. A point collocation technique is then used to match the acoustic fields (pressure and axial acoustic velocity) at the geometric discontinuities between the silencer chamber and the inlet and outlet pipes. Transmission loss predictions are compared favorably with a general three-dimensional finite element approach, offering a reduction in the computational effort.

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Section: Introductionmentioning

confidence: 99%

Point collocation scheme in silencers with temperature gradient and mean flow

Denia

Sánchez-Orgaz

Baeza

et al. 2016

Journal of Computational and Applied Mathematics

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“…A reactive silencer is presented whose temperature variation is ΔTax = 200 °C approximately, with Ti = 510 °C and To = 315 °C. Transversal temperature variations ΔTrad can be also significant in exhaust silencers, and thermal gradients higher than 100 °C can be found in the literature [17], resulting in complex profiles of the relevant acoustic properties.…”

Section: Temperature Fieldmentioning

confidence: 99%

“…Significant temperature variations can be found along the exhaust system of internal combustion engines [14][15][16][17][18]. Concerning the acoustic performance of silencers, it is straightforward to account for the effects of uniform high temperature fields if only reactive elements are present [19], since attenuation curves at different temperatures overlap when a normalized frequency f/c is considered, c being the speed of sound at working temperature T [20].…”

Section: Introductionmentioning

confidence: 99%

“…The temperature field is assumed one-dimensional in the central passage, reaching its maximum value at the inlet while decreasing gradually along the flow path [14,16,17,18,21,23]. A more general multidimensional function T(x,y,z) = T(x) is considered in the chamber [17]. Temperature variations in the silencer lead to heterogeneous properties in the propagation media as well as spatial dependence of the acoustic impedance p Z  corresponding to the perforated duct.…”

Section: Introductionmentioning

confidence: 99%

“…The corresponding boundary surfaces are denoted by Γa and Γm, respectively, the inlet and outlet sections are represented by Γi and Γo, and the perforated surface is Γp. The temperature field is assumed one-dimensional in the central passage, reaching its maximum value at the inlet while decreasing gradually along the flow path [14,16,17,18,21,23]. A more general multidimensional function T(x,y,z) = T(x) is considered in the chamber [17].…”

Section: Introductionmentioning

confidence: 99%

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Finite element based acoustic analysis of dissipative silencers with high temperature and thermal-induced heterogeneity

Denia

Sánchez-Orgaz

Martínez‐Casas

et al. 2015

Finite Elements in Analysis and Design

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A mixed finite element model has been derived for the acoustic analysis of perforated dissipative silencers including several effects simultaneously: (1) High temperature and thermal gradients in the central duct and the outer absorbent material; (2) A perforated passage carrying non-uniform axial mean flow. For such a combination, the properties of sound propagation media and flow are inhomogeneous and vary with position. The material of the outer chamber can be modelled by its complex equivalent acoustic properties, which completely determine the propagation of sound waves in the air contained in the absorbent medium. Temperature gradients introduce variations in these properties that can be evaluated through a heterogeneous temperature-dependent resistivity in combination with material models obtained at room temperature. A pressure-based wave equation for stationary medium is then used with the equivalent density and speed of sound of the absorbent material varying as functions of the spatial coordinates. Regarding the central air passage, a wave equation in terms of acoustic velocity potential can be used to model the non-uniform moving medium since the presence of temperature variations introduce not only heterogeneous acoustic properties of the air but also a gradient in the mean flow velocity. The acoustic connection between the central passage and the outer chamber is given by the acoustic impedance of the perforated duct. This impedance depends on the heterogeneous properties of the absorbent material and the non-uniform mean flow, leading to a spatial variation of the acoustic coupling and also to additional convective terms in the governing equations. The results presented show the influence of temperature, thermal gradients and mean flow on the transmission loss of automotive silencers. It has been found that high temperature and thermal-induced heterogeneity can have a significant influence on the acoustic attenuation of an automotive silencer and so should be included in theoretical models. In some particular configurations it may be relatively accurate to approximate the temperature field by using a uniform profile with an average value, specially for low resistivity materials. It has been shown, however, that this is not always possible and attenuation overestimation is likely to be predicted, mainly for high radial thermal gradients and high material flow resistivities, if the temperature distribution is not taken into account.

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Simulation Research of Vehicle Exhaust System Hanger Location

Zhang

Song

2012

AMR

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To reduce the impact of exhaust system hanger layout on the vehicle vibration performance and research the method about the reasonable layout of the hanger, forst established the FE model of an automotive exhaust system and fixed up hanger locations by modal analysis and load distribution by statics analysis. Then according to the displacement and force response to the engine’s torque loaded on powertrain’s mass centroid, adjusted hanger locations. At last, got the reasonable hanger location layout. The exhaust system hanger layout is used on a heavy truck and has the obvious effect.

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Flow Field Analysis and Improvement of Automobile Exhaust System Cold End

Cited by 4 publications

References 1 publication

Point collocation scheme in silencers with temperature gradient and mean flow

Point collocation scheme in silencers with temperature gradient and mean flow

Finite element based acoustic analysis of dissipative silencers with high temperature and thermal-induced heterogeneity

Simulation Research of Vehicle Exhaust System Hanger Location

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