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Procedure to estimate the in-duct sound power in the high frequency range with non-plane waves
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för industriell teknik och management (ITM), Centra, Competence Center for Gas Exchange (CCGEx).ORCID-id: 0000-0001-7898-8643
2012 (engelsk)Inngår i: ASME 2012 Noise Control and Acoustics Division Conference at InterNoise 2012, ASME Press, 2012, s. 181-191Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

The acoustic characterization of fluid machines, e.g., internal combustion engines, compressors, or fans is of great importance when designing the connected duct systems and its silencers. For machines connected to large ducts where also the non-plane wave range is important, for instance large diesels and gas turbines, a suitable way to characterize the source is to determine the sound power under reflection free conditions. For the low frequency plane wave range in-duct sound power can be measured with the widely used two microphone method. The goal of this study is to investigate how, starting from the two-microphone approach, a suitable wall mounted microphone configuration can be defined and used to estimate the propagating in-duct sound power also beyond the plane wave range. For this purpose an acoustic source test-rig was built and numerical simulations were also conducted. The in-duct sound power from monopole, dipole, and quadrupole source types was determined using twelve wall mounted microphones and cross-spectra averaging methods. The in-duct results were compared against sound power measured using the reverberation room method (ISO 3741). Based on the simulations and the experimental results the best microphone positions and weighting factors were determined.

sted, utgiver, år, opplag, sider
ASME Press, 2012. s. 181-191
Emneord [en]
Acoustic characterization, Acoustic sources, Averaging method, Frequency ranges, Microphone positions, Reverberation rooms, Two-microphone methods, Weighting factors
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-144786DOI: 10.1115/NCAD2012-0531ISI: 000323912200019Scopus ID: 2-s2.0-84884857493ISBN: 978-079184532-5 (tryckt)OAI: oai:DiVA.org:kth-144786DiVA, id: diva2:717886
Konferanse
ASME 2012 Noise Control and Acoustics Division Conference at InterNoise 2012, NCAD 2012; New York City, NY; United States; 19 August 2012 through 22 August 2012
Merknad

QC 20140519

Tilgjengelig fra: 2014-05-19 Laget: 2014-04-29 Sist oppdatert: 2015-11-19bibliografisk kontrollert
Inngår i avhandling
1. Acoustic In-duct Characterization of Fluid Machines with Applications to Medium Speed IC-engines
Åpne denne publikasjonen i ny fane eller vindu >>Acoustic In-duct Characterization of Fluid Machines with Applications to Medium Speed IC-engines
2015 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The unwanted sound, noise, can lead to health problems, e.g. hearing loss and stress-related problems. A pre-knowledge of noise generation by machines is of great importance due to the ever-shorter product development cycles and stricter noise legislation. The noise from a machine radiates to the environment indirectly via the foundation structure and directly via the surrounding fluid. A fluid machine converts the energy from the fluid into mechanical energy or vice versa. Examples of the fluid machines are internal combustion engines (IC-engines), pumps, compressors, and fans. Predicting and controlling noise from a fluid machine requires a model of the noise sources themselves, i.e. acoustic source data. In the duct systems connected to the fluid machines, the acoustic source interacts strongly with the system boundaries, and the source characteristics must be described using in-duct methods.

Above a certain frequency, i.e. first non-plane wave mode cut-on frequency, the sound pressure varies over the duct cross-section and non-plane waves are introduced. For a number of applications, the plane wave range dominates and the non-plane waves can be neglected. But for machines connected to large ducts, the non-plane wave range is also important. In the plane wave range, one-dimensional process simulation software can be used to predict, e.g. for IC-engines, the acoustic in-duct source characteristics. The high frequency phenomena with non-plane waves are so complicated, however, that it is practically impossible to simulate them accurately. Thus, in order to develop methods to estimate the sound produced, experimental studies are also essential.

This thesis investigates the acoustic in-duct source characterization of fluid machines with applications to exhaust noise from medium speed IC-engines.  This corresponds to large engines used for power plants or on ships, for which the non-plane wave range also becomes important. The plane wave source characterization methods are extended into the higher frequency range with non-plane waves. In addition, methods to determine non-plane wave range damping for typical elements in exhaust systems, e.g. after-treatment devices, are discussed.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2015. s. xi, 63
Serie
TRITA-AVE, ISSN 1651-7660 ; 2015:86
Emneord
in-duct, acoustic source, source characterization, IC-engine
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-177341 (URN)978-91-7595-765-4 (ISBN)
Disputas
2015-12-10, sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

QC 20151119

Tilgjengelig fra: 2015-11-19 Laget: 2015-11-18 Sist oppdatert: 2015-12-14bibliografisk kontrollert

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