Linearity Tests for in-Duct Acoustic One-Port Sources

Bodén, Hans; Albertson, Fredrik

doi:10.1006/jsvi.2000.3034

Cited by 40 publications

(8 citation statements)

References 10 publications

(16 reference statements)

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“…For this, Boden's linearity test 8,14 has been carried out at two measurement points, one upstream (dirty side) of the filter and another downstream (cleaner side) of the filter, near the intake manifold. Linearity coefficient of an over-determined system, A.x = b, is defined as…”

Section: Resultsmentioning

confidence: 99%

“…(14), the least square fit of different values of A obtained from their respective SSL spectra corresponding to various values of the air-fuel ratio AFR are found to follow the relation …”

Section: The Values Of a And B Of Ssl For The Turbocharged Enginementioning

confidence: 99%

“…(14) for different speed orders, and then, the source pressure p s can be calculated using Eqn. (10).…”

Section: Values Of a And B For Naturally Aspirated Enginementioning

confidence: 99%

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Intake source characterization of a compression ignition engine: Empirical expressions

Hota¹,

Munjal²

2008

Noise Control Eng. J.

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Unlike exhaust noise, the intake system noise of an automobile cannot be measured because of the proximity of the engine at the point of measurement. Besides, the intake side is associated with turbocharger (booster), intercooler, cooling fan, etc., which will make the measurement of the intake noise erroneous. Therefore, in the present investigation, the source characteristics of the intake system have been expressed as functions of the engine's physical, operating and thermodynamic parameters. The pressure time history is first computed by means of the commercial software AVL-BOOST for different acoustic loads (induction pipe lengths), which are then used to determine source characteristics, i.e., p s and Z s (analogous to the open-circuit voltage and internal impedance of an electrical source), using an appropriate multi-load method. This investigation has been conducted for both naturally aspirated and turbocharged diesel engine. Using this methodology and the resultant empirical relations, one can analyze any compression-ignition (CI) engine configuration for the prediction of the un-muffled noise without having to carry out the rather cumbersome and time-consuming time-domain simulation of the intake side. The aim of the present study is to parameterize the source characteristics of an engine in terms of basic engine parameters, so that a first assessment of the un-muffled intake noise can be made by means of the frequency-domain transfer matrix method before a detailed design is taken up. © 2008 Institute of Noise Control Engineering.

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Section: Resultsmentioning

confidence: 99%

“…(14), the least square fit of different values of A obtained from their respective SSL spectra corresponding to various values of the air-fuel ratio AFR are found to follow the relation …”

Section: The Values Of a And B Of Ssl For The Turbocharged Enginementioning

confidence: 99%

See 1 more Smart Citation

Intake source characterization of a compression ignition engine: Empirical expressions

Hota¹,

Munjal²

2008

Noise Control Eng. J.

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“…Although the technique is quite useful in tuning the whole piping system in the viewpoint of engine performance, it has limitation in calculation speed and computer memory space for the acoustic analysis, in particular due to the geometrical complexity. Lavrentjev et al [6] and Bodén and Albertson [7] suggested techniques which can be used for testing the linearity of the target noise source. In many cases, without loss of generality, automotive intake and exhaust systems are considered as pseudo-linear systems and a linear acoustic analysis technique is usually employed.…”

Section: Introductionmentioning

confidence: 99%

Prediction of intake noise of an automotive engine in run-up condition

Kim

Lee

et al. 2009

Applied Acoustics

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“…The purpose of the present paper is to study nonlinear energy transfer for high level acoustic excitation using techniques similar to acoustic multi-port source characterization techniques developed for studying the interaction between acoustic sources and connected duct systems. [23][24][25][26] If linear system identification theory is used it is assumed that superposition applies and that the functions studied are analytical at each level of excitation. Polyharmonic distortion (PHD) modeling, [27][28][29] used for studying the nonlinear properties of microwave systems, does not assume analytic functions nor does it assume application of normal superposition.…”

Section: Introductionmentioning

confidence: 99%

Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation

Bodén

2011

The Journal of the Acoustical Society of America

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This paper discusses experimental techniques for obtaining the acoustic properties of in-duct samples with non-linear acoustic characteristic. The methods developed are intended both for studies of non-linear energy transfer to higher harmonics for samples only accessible from one side such as wall treatment in aircraft engine ducts or automotive exhaust systems and for samples accessible from both sides such as perforates or other top sheets. When harmonic sound waves are incident on the sample nonlinear energy transfer results in sound generation at higher harmonics at the sample (perforate) surface. The idea is that these sources can be characterized using linear system identification techniques similar to one-port or two-port techniques which are traditionally used for obtaining source data for in-duct sources such as IC-engines or fans. The starting point will be so called polyharmonic distortion modeling which is used for characterization of nonlinear properties of microwave systems. It will be shown how acoustic source data models can be expressed using this theory. Source models of different complexity are developed and experimentally tested. The results of the experimental tests show that these techniques can give results which are useful for understanding non-linear energy transfer to higher harmonics.

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Linearity Tests for in-Duct Acoustic One-Port Sources

Cited by 40 publications

References 10 publications

Intake source characterization of a compression ignition engine: Empirical expressions

Intake source characterization of a compression ignition engine: Empirical expressions

Prediction of intake noise of an automotive engine in run-up condition

Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation

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