Change search
ReferencesLink to record
Permanent link

Direct link
IC-engine intake acoustic source data from non-linear simulations
Volvo Car Corporation, Sweden .
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. (CICERO)ORCID iD: 0000-0002-8474-8563
2007 (English)In: SAE technical paper series, ISSN 0148-7191Article in journal (Refereed) Published
Abstract [en]

Non-linear 1-D CFD time domain prediction codes are used to calculate the performance of the gas exchange process for IC-engines. These softwares give time-varying pressures and velocities in the exhaust and intake systems. They could therefore in principle be used to predict radiated orifice noise. However, the accuracy is not sufficient for them to be used as a virtual design tool. More accurate results might be provided by dividing the problem into a source domain and a transmission domain and use linear 3-D frequency domain codes to describe the transmission part. Radiated shell noise and frequency dependent damping could also be included in the frequency domain models. The simplest source model used in the low frequency plane wave range for simulation of dominating engine harmonics is the linear time invariant 1-port model. This acoustic source data is usually obtained from experimental tests where the multi-load methods and especially the two-load method are most commonly used. The main limitations of these tests are that they are time consuming, expensive and require physical hardware which prevents them from being used for early predictions. It would therefore be of interest to extract the acoustic source data from the existing 1-D CFD gas exchange models. This paper presents a comparison between acoustic source data, obtained applying the two-load technique to measurements on a six-cylinder personal car petrol engine, and to 1-D simulations of identical intake systems on the same engine. The degree of non-linearity in the results is discussed as well as the choice of source type and its relation to engine properties. The results show that it is possible to obtain reasonably accurate source strength as well as source impedance estimates, for the intake side, from 1-D gas exchange simulations.

Place, publisher, year, edition, pages
Keyword [en]
Acoustic noise measurement, Acoustics, Computer simulation, Engine cylinders, Engines, Exhibitions, Frequency domain analysis, Intake systems, Time domain analysis
National Category
Vehicle Engineering
URN: urn:nbn:se:kth:diva-14191DOI: 10.4271/2007-01-2209ScopusID: 2-s2.0-84877431697OAI: diva2:331672
Noise and Vibration Conference and Exhibition; St. Charles, IL; United States; 15 May 2007 through 17 May 2007

QC 20100723

Available from: 2010-07-23 Created: 2010-07-23 Last updated: 2014-11-28Bibliographically approved
In thesis
1. Modelling of IC-Engine Intake Noise
Open this publication in new window or tab >>Modelling of IC-Engine Intake Noise
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Shorter product development cycles, densely packed engine compartments and intensified noiselegislation increase the need for accurate predictions of IC-engine air intake noise at earlystages. The urgent focus on the increasing CO2 emissions and the efficiency of IC-engines, aswell as new techniques such as homogeneous charge compression ignition (HCCI) mightworsen the noise situation. Nonlinear one-dimensional (1D) gas dynamics time-domainsimulation software packages are used within the automotive industry to predict intake andexhaust orifice noise. The inherent limitation of 1D plane wave propagation, however, limitsthis technique to sufficiently low frequencies where non-plane wave effects are small. Thereforethis type of method will first fail in large components such as air cleaners. Further limitations,that might not be important for simulation of engine performance but indeed for acoustics,include difficulties to apply frequency dependent boundary conditions and losses as well as toinclude effects of vibrating walls.

The first part of this thesis treats two different strategies to combine nonlinear and linearmodelling of intake systems in order to improve the accuracy of the noise predictions. Paper Adescribes how a linear time-invariant one-port source model can be extracted using nonlineargas dynamics simulations. Predicted source data for a six-cylinder naturally aspirated engine isvalidated using experimental data obtained from engine test bench measurements. Paper Bpresents an experimental investigation on the influence of mean flow and filter paper on theacoustics of air intake systems. It also suggests how a linear source, extracted from nonlinearsimulations can be coupled to acoustic finite elements describing the intake system and toboundary elements describing the radiation to the surroundings. Simulations and measurementsare carried out for a large number of engine revolution speeds in order to make the firstsystematic validation of an entirely virtual intake noise model that includes 3D effects for awide engine speed range. In Paper C an initial study on a new technique for the use of two-portsin the time domain for automotive gas dynamics applications is presented. Tabulated frequencydomaintwo-port data representing an air cleaner unit on the impedance form is inverselytransformed to the time domain and used as FIR filters in nonlinear time-domain calculations.

The second part of the thesis considers detailed modelling of sound propagation in capillarytubes. Thermoviscous boundary effects and interaction between sound waves and turbulencecan, for sufficiently narrow tubes, yield significant attenuation. Several components in the gasexchange system of IC-engines are based on arrays of narrow ducts and might haveunderestimated silencing capabilities. In particular the sound transmission properties of chargeair coolers (CAC) have so far gained interest from very few authors. In Paper D a detailedinvestigation of the acoustic properties of CACs is presented. As a result the first linearfrequency-domain model for CACs, which includes a complete treatment of losses in the narrowtubes and 3D effects in the connecting tanks, is proposed. Interesting low frequency dampingmost likely due to interaction between sound and turbulence is observed in the experimentaldata. A new numerical model that describes this dissipative effect in narrow tubes is suggestedin Paper E. Validation is carried out using experimental data from the literature. Finally, inPaper F the CAC-model presented in Paper D is updated with the new model for interactionbetween turbulence and acoustic waves proposed in Paper E. The updated model is shown toyield improved predictions.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. xvi, 32 p.
Trita-AVE, ISSN 1651-7660 ; 2009:16
IC-engine, intake noise, gas dynamics, linear source data, frequency domain, 2-port, losses, air cleaner unit, filter paper, flow, FEM, BEM, charge air cooler, narrow tube
National Category
Fluid Mechanics and Acoustics
urn:nbn:se:kth:diva-10549 (URN)
Public defence
2009-06-01, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 13:15 (English)
QC 20100723Available from: 2009-05-26 Created: 2009-05-26 Last updated: 2010-07-23Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Knutsson, MagnusBodén, Hans
By organisation
Aeronautical and Vehicle Engineering
In the same journal
SAE technical paper series
Vehicle Engineering

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 75 hits
ReferencesLink to record
Permanent link

Direct link