Estimating the high frequency in-duct sound power using sound pressures at the duct wall

Antti Hynninen, M. Åbom

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

When studying the acoustic wave propagation in a channel, the frequency range can be divided to the low frequency plane wave range and to the high frequency range with non-plane waves. In the low frequency range the wave propagation is one-dimensional and the governing equations are rather simple. The larger the duct the lower the frequency limit of the non-plane waves. Therefore taking into account also the three-dimensional acoustic wave propagation is important especially when considering the duct systems used in large structures, e.g., medium speed internal combustion engines (IC-engines), fans, or compressors. Harsh environment and unmovable structures restrict the use of standardized noise measuring methods. To characterize the medium speed IC-engine exhaust noise in situ, the in-duct sound pressures are measured using wall mounted transducers. Then the source sound power is estimated from the propagating sound pressures, which is the power based approach. The power based approach is only valid in frequency averaged sense and therefore the source power must be defined in one-third octave frequency bands, for example. One way to estimate the source sound power in the high frequency range, is to extend the classical plane wave formulation by defining the one-third octave frequency band weighting factors for different excitation types. The aim of this study is to define these weighting factors using finite element method (FEM) simulations of a test duct with non-reflecting terminations. The sound pressures at the duct wall were compared to the sound pressures at the duct end for randomized multi-modal excitations. From statistics, the one-third octave band weighting factors and their reliability were estimated.
Original languageEnglish
Title of host publicationProceeding of the 20th International Congress on Sound and Vibration 2013
EditorsMalcolm J. Crocker, Marek Pawelczyk, Boonchoat Paosawatyanyong
PublisherInternational Institute of Acoustics and Vibration IIAV
Pages2553-2559
Volume3
ISBN (Print)978-1-62993-150-0
Publication statusPublished - 2013
MoE publication typeA4 Article in a conference publication
Event20th International Congress on Sound and Vibration - Bangkok, Thailand
Duration: 7 Jul 201311 Jul 2013

Conference

Conference20th International Congress on Sound and Vibration
Abbreviated titleICSV 20
CountryThailand
CityBangkok
Period7/07/1311/07/13

Fingerprint

sound pressure
ducts
estimating
acoustics
octaves
frequency ranges
wave propagation
internal combustion engines
plane waves
low frequencies
compressors
fans
excitation
finite element method
transducers
statistics
formulations
estimates
simulation

Keywords

  • high frequency range
  • in-duct sound power
  • acoustic source characteristics

Cite this

Hynninen, A., & Åbom, M. (2013). Estimating the high frequency in-duct sound power using sound pressures at the duct wall. In M. J. Crocker, M. Pawelczyk, & B. Paosawatyanyong (Eds.), Proceeding of the 20th International Congress on Sound and Vibration 2013 (Vol. 3, pp. 2553-2559). International Institute of Acoustics and Vibration IIAV.
Hynninen, Antti ; Åbom, M. / Estimating the high frequency in-duct sound power using sound pressures at the duct wall. Proceeding of the 20th International Congress on Sound and Vibration 2013. editor / Malcolm J. Crocker ; Marek Pawelczyk ; Boonchoat Paosawatyanyong. Vol. 3 International Institute of Acoustics and Vibration IIAV, 2013. pp. 2553-2559
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title = "Estimating the high frequency in-duct sound power using sound pressures at the duct wall",
abstract = "When studying the acoustic wave propagation in a channel, the frequency range can be divided to the low frequency plane wave range and to the high frequency range with non-plane waves. In the low frequency range the wave propagation is one-dimensional and the governing equations are rather simple. The larger the duct the lower the frequency limit of the non-plane waves. Therefore taking into account also the three-dimensional acoustic wave propagation is important especially when considering the duct systems used in large structures, e.g., medium speed internal combustion engines (IC-engines), fans, or compressors. Harsh environment and unmovable structures restrict the use of standardized noise measuring methods. To characterize the medium speed IC-engine exhaust noise in situ, the in-duct sound pressures are measured using wall mounted transducers. Then the source sound power is estimated from the propagating sound pressures, which is the power based approach. The power based approach is only valid in frequency averaged sense and therefore the source power must be defined in one-third octave frequency bands, for example. One way to estimate the source sound power in the high frequency range, is to extend the classical plane wave formulation by defining the one-third octave frequency band weighting factors for different excitation types. The aim of this study is to define these weighting factors using finite element method (FEM) simulations of a test duct with non-reflecting terminations. The sound pressures at the duct wall were compared to the sound pressures at the duct end for randomized multi-modal excitations. From statistics, the one-third octave band weighting factors and their reliability were estimated.",
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Hynninen, A & Åbom, M 2013, Estimating the high frequency in-duct sound power using sound pressures at the duct wall. in MJ Crocker, M Pawelczyk & B Paosawatyanyong (eds), Proceeding of the 20th International Congress on Sound and Vibration 2013. vol. 3, International Institute of Acoustics and Vibration IIAV, pp. 2553-2559, 20th International Congress on Sound and Vibration, Bangkok, Thailand, 7/07/13.

Estimating the high frequency in-duct sound power using sound pressures at the duct wall. / Hynninen, Antti; Åbom, M.

Proceeding of the 20th International Congress on Sound and Vibration 2013. ed. / Malcolm J. Crocker; Marek Pawelczyk; Boonchoat Paosawatyanyong. Vol. 3 International Institute of Acoustics and Vibration IIAV, 2013. p. 2553-2559.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

TY - GEN

T1 - Estimating the high frequency in-duct sound power using sound pressures at the duct wall

AU - Hynninen, Antti

AU - Åbom, M.

N1 - Project: 82112

PY - 2013

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N2 - When studying the acoustic wave propagation in a channel, the frequency range can be divided to the low frequency plane wave range and to the high frequency range with non-plane waves. In the low frequency range the wave propagation is one-dimensional and the governing equations are rather simple. The larger the duct the lower the frequency limit of the non-plane waves. Therefore taking into account also the three-dimensional acoustic wave propagation is important especially when considering the duct systems used in large structures, e.g., medium speed internal combustion engines (IC-engines), fans, or compressors. Harsh environment and unmovable structures restrict the use of standardized noise measuring methods. To characterize the medium speed IC-engine exhaust noise in situ, the in-duct sound pressures are measured using wall mounted transducers. Then the source sound power is estimated from the propagating sound pressures, which is the power based approach. The power based approach is only valid in frequency averaged sense and therefore the source power must be defined in one-third octave frequency bands, for example. One way to estimate the source sound power in the high frequency range, is to extend the classical plane wave formulation by defining the one-third octave frequency band weighting factors for different excitation types. The aim of this study is to define these weighting factors using finite element method (FEM) simulations of a test duct with non-reflecting terminations. The sound pressures at the duct wall were compared to the sound pressures at the duct end for randomized multi-modal excitations. From statistics, the one-third octave band weighting factors and their reliability were estimated.

AB - When studying the acoustic wave propagation in a channel, the frequency range can be divided to the low frequency plane wave range and to the high frequency range with non-plane waves. In the low frequency range the wave propagation is one-dimensional and the governing equations are rather simple. The larger the duct the lower the frequency limit of the non-plane waves. Therefore taking into account also the three-dimensional acoustic wave propagation is important especially when considering the duct systems used in large structures, e.g., medium speed internal combustion engines (IC-engines), fans, or compressors. Harsh environment and unmovable structures restrict the use of standardized noise measuring methods. To characterize the medium speed IC-engine exhaust noise in situ, the in-duct sound pressures are measured using wall mounted transducers. Then the source sound power is estimated from the propagating sound pressures, which is the power based approach. The power based approach is only valid in frequency averaged sense and therefore the source power must be defined in one-third octave frequency bands, for example. One way to estimate the source sound power in the high frequency range, is to extend the classical plane wave formulation by defining the one-third octave frequency band weighting factors for different excitation types. The aim of this study is to define these weighting factors using finite element method (FEM) simulations of a test duct with non-reflecting terminations. The sound pressures at the duct wall were compared to the sound pressures at the duct end for randomized multi-modal excitations. From statistics, the one-third octave band weighting factors and their reliability were estimated.

KW - high frequency range

KW - in-duct sound power

KW - acoustic source characteristics

M3 - Conference article in proceedings

SN - 978-1-62993-150-0

VL - 3

SP - 2553

EP - 2559

BT - Proceeding of the 20th International Congress on Sound and Vibration 2013

A2 - Crocker, Malcolm J.

A2 - Pawelczyk, Marek

A2 - Paosawatyanyong, Boonchoat

PB - International Institute of Acoustics and Vibration IIAV

ER -

Hynninen A, Åbom M. Estimating the high frequency in-duct sound power using sound pressures at the duct wall. In Crocker MJ, Pawelczyk M, Paosawatyanyong B, editors, Proceeding of the 20th International Congress on Sound and Vibration 2013. Vol. 3. International Institute of Acoustics and Vibration IIAV. 2013. p. 2553-2559