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Optimization of exhaust systems to meet the acoustic regulations and the enginespecifications
Ain Shams Univeristy, Group for Advanced Resaerch in Dynamic Systems, Faculty of Engineering, Egypt.
Ain Shams Univeristy, Group for Advanced Resaerch in Dynamic Systems, Faculty of Engineering, Egypt.
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strömningsakustik.ORCID-id: 0000-0003-4103-0129
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strömningsakustik.ORCID-id: 0000-0001-7898-8643
2011 (Engelska)Konferensbidrag, Publicerat paper (Övrigt vetenskapligt)
Abstract [en]

Mufflers for internal combustion engines should be carefully designed. The main objective of a muffler is to reduce the engine noise while maintaining the back pressure below a certain limit. A specific target acoustic performance has to be met under space constraints and allowable engine back pressure limit. Usually, the insertion loss of the exhaust system is required to satisfy a certain target performance curve. The insertion loss is most appropriate to describe the exhaust system acoustic performance since it is dependent on the engine acoustic impedance, which varies with the engine loading and rotational speed. In this paper, a muffler optimization problem is formulated so that several shape parameters are optimized under some space constraints with flow. Any combination of linear space constraints can be imposed. The allowable engine back pressure is introduced as a non-linear constraint so that the optimum shape design will meet the engine back pressure specifications. The interior point optimization algorithm, which is available as a built-in MATLAB function "fmincon", is used in this paper. The formulated problem is applied to a real case study, where a truck exhau stsystem consists of a diesel engine, two mufflers, intermediate pipes, and a tailpipe. The first muffler is a typical EU-regulation compliant. The dimensions and location of the second muffler are to be optimized. A limit for the system back pressure is imposed by the engine manufacturer. An optimum design was investigated for different engine speeds and loadings. It was found that using the suggested formulation in this paper; one can obtain an applicable design of a muffler to meet both the acoustic regulations and the engine specifications.

Ort, förlag, år, upplaga, sidor
2011.
Nationell ämneskategori
Strömningsmekanik och akustik
Identifikatorer
URN: urn:nbn:se:kth:diva-103698Scopus ID: 2-s2.0-84871490374OAI: oai:DiVA.org:kth-103698DiVA, id: diva2:561282
Konferens
18th International Congressof Sound and Vibration, Rio De Janeiro (2011)
Anmärkning

QC 20121018

Tillgänglig från: 2012-10-18 Skapad: 2012-10-18 Senast uppdaterad: 2016-09-20Bibliografiskt granskad
Ingår i avhandling
1. Investigation and Optimization of the Acoustic Performance of Exhaust Systems
Öppna denna publikation i ny flik eller fönster >>Investigation and Optimization of the Acoustic Performance of Exhaust Systems
2012 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

There is a strong competition among automotive manufacturers to reduce the radiated noise levels. One important source is the engine exhaust where the main noise control strategy is by using efficient mufflers. Stricter vehicle noise regulations combined with various exhaust gas cleaning devices, removing space for traditional mufflers, are also creating new challenges. Thus, it is crucial to have efficient models and tools to design vehicle exhaust systems. In addition the need to reduce CO2 emissions puts requirements on the losses and pressure drop in exhaust systems. In this thesis a number of problems relevant for the design of modern exhaust systems for vehicles are addressed. First the modelling of perforated mufflers is investigated. Fifteen different configurations were modeled and compared to measurements using 1D models. The limitations of using 1D models due to 3D or non-plane wave effects are investigated. It is found that for all the cases investigated the 1D model is valid at least up to half the plane wave region. But with flow present, i.e., as in the real application the 3D effects are much less important and then normally a 1D model works well. Another interesting area that is investigated is the acoustic performance of after treatment devices. Diesel engines produce harmful exhaust emissions and high exhaust noise levels. One way of mitigating both exhaust emissions and noise is via the use of after treatment devices such as Catalytic Converters (CC), Selective Catalytic Reducers (SCR), Diesel Oxidation Catalysts (DOC), and Diesel Particulate Filters (DPF). The objective of this investigation is to characterize and simulate the acoustic performance of different types of filters so that maximum benefit can be achieved. A number of after treatment device configurations for trucks were selected and investigated.

Finally, addressing the muffler design constraints, i.e., concerning space and pressure drop, a muffler optimization problem is formulated achieving the optimum muffler design through calculating the acoustic properties using an optimization technique. A shape optimization approach is presented for different muffler configurations, and the acoustic results are compared against optimum designs from the literature obtained using different optimization methods as well as design targets.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2012. s. iv, 18
Serie
Trita-AVE, ISSN 1651-7660 ; 2012:31
Nyckelord
Exhaust systems, noise, pressure drop, 1D models, perforated mufflers, after treatment devices, optimization
Nationell ämneskategori
Strömningsmekanik och akustik
Identifikatorer
urn:nbn:se:kth:diva-103595 (URN)
Presentation
2012-10-14, Faculty of Engineering, Ain Shams university, Kairo, Egypt, 09:15 (Engelska)
Opponent
Handledare
Forskningsfinansiär
TrenOp, Transport Research Environment with Novel Perspectives
Anmärkning

QC 20121016

Tillgänglig från: 2012-10-16 Skapad: 2012-10-16 Senast uppdaterad: 2013-04-11Bibliografiskt granskad

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