Experimental Two-Port Characterization of the Aeroacoustic Transmission Properties of a Truck's Exhaust System

Roeck, Wim De; Nordström, Lars; Englund, Thomas; Desmet, Wim

doi:10.4271/2012-01-1558

Cited by 3 publications

(2 citation statements)

References 19 publications

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“…where z i represents the location of microphone i with respect to the reference position at the in-or outlet of the two-port element, k + ≈ k/(1 + M ) and k − ≈ k/(1 − M ) are the acoustic wave numbers of the upand downstream propagating waves and ⊗ represents the Moore-Penrose pseudo matrix inverse. A further reduction of the measurement uncertainties can be obtained by using an iterative procedure to solve for certain environmental variables, as described in references 45,46 . The determination of the scatter matrix coefficients requires at least two independent measurements.…”

Section: Impedance Eduction Techniquesmentioning

confidence: 99%

Combined Numerical and Experimental Study of a Slit Resonator Under Grazing Flow

Denayer

Tournadre

Roeck

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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This study compares two numerical methods based on the Linearized Navier-Stokes equations (LNSE) for the simulation of a resonator in presence of a cold mean flow: a time domain Runge-Kutta Discontinuous Galerkin (RKDG) code and a frequency-domain high-order continuous Finite Element Method (pFEM). The results are compared to experimental data from a dedicated experimental campaign on a slit resonator. It was shown that the simulations predict the correct trends, but some discrepancies have been observed. The origin of these differences has to be investigated further. Different impedance measurement techniques are applied to the numerical and experimental data to obtain the acoustic impedance of the slit resonator. Within their respective range of validity, reasonable agreement is found between the different techniques. Nomenclature B Width of the duct, [m] Z Acoustic impedance, [Rayl] c Speed of sound, [m/s] z Specific impedance, [-] f Frequency, [Hz] z i Location of microphone i, [m] k Acoustic wave number, [m −1 ] δ Flow boundary layer thickness, [m] H Back cavity depth, [m] δ ij Kronecker delta function, [-] L Length of the test section, [m] Acoustic monopole source amplitude, [P a] M Mach number, [-] κ Thermal conductivity, [W/(m.K)] p Pressure, [P a] λ Acoustic wavelength, [m] R +/− Reflection coefficient of scatter matrix, [-] µ Dynamic viscosity, [kg/(m.s)] S Cross section of the channel, [m 2 ] ν Kinematic viscosity, [m 2 /s] S c Surface of perforation, [m 2 ] τ Viscous stress tensor, [P a] T Absolute temperature, [K] Φ Dissipation function, [W/m 3 ] T +/− Transmission coefficient of the scatter matrix, [-] ρ Density, [kg/m 3 ] u Velocity vector, [m/s] ω Angular frequency, [rad/s] x Vector of the cartesian coordinate position, [m]

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Section: Impedance Eduction Techniquesmentioning

confidence: 99%

Combined Numerical and Experimental Study of a Slit Resonator Under Grazing Flow

Denayer

Tournadre

Roeck

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

Self Cite

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“…The idea of estimating the acoustic model parameters in a waveguide with the help of several measurements is also applied in (Boonen et al, 2009;De Roeck et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Calibration of Multiple Microphones for Both Phase and Amplitude in an Impedance Tube

Tóth¹,

Schram²

2015

Archives of Acoustics

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This paper presents and compares microphone calibration methods for the simultaneous calibration of small electret microphones in a wave guide. The microphones are simultaneously calibrated to a reference microphone both in amplitude and phase. The calibration procedure is formulated on the basis of the damped plane wave propagation equation, from which the acoustics field along the wave guide is predicted, using several reference measurements. Different calibration models are presented and the methods were found to be sensitive to the formulation, as well as to the number of free parameters used during the reconstruction of the wave-field. The wave guide model based on five free parameters was found to be the preferred method for this type of calibration procedure.

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Multi-port Characterization of a Modal Filter Containing Micro-perforated Panels

Denayer

Korchagin

Roeck

et al. 2016

22nd AIAA/CEAS Aeroacoustics Conference

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Experimental Two-Port Characterization of the Aeroacoustic Transmission Properties of a Truck's Exhaust System

Cited by 3 publications

References 19 publications

Combined Numerical and Experimental Study of a Slit Resonator Under Grazing Flow

Combined Numerical and Experimental Study of a Slit Resonator Under Grazing Flow

Simultaneous Calibration of Multiple Microphones for Both Phase and Amplitude in an Impedance Tube

Multi-port Characterization of a Modal Filter Containing Micro-perforated Panels

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