To be able to predict the sound pressure level emitted by a exhaust system one must be able to describe the source. The source in the form of an engine can linearly be described as a source strength and a source impedance. An IC-engine can acoustically have a non-linear part meaning that the source characteristics have a dependency on the load. The first part of this work investigates through simulation's in GT-Power how these characteristics are affected by the load connected to the source. The Second part of the work combines the source characteristics with simulations of a muffler and compares to different methods of getting the pressure at the outlet of the exhaust. The first method is direct simulation of the muffler in COMSOL Multiphysics and the second is a transfer matrix based calculation. How sensitive the results at the outlet are to changes in the source impedance is also tested. It is concluded that using five loads for the multiload method in the form of five different lengths on the pipe connecting the engine and muffler works when the pipe have the same length as would be seen in reality. Furthermore, the pipe lengths should have a small range, 100 mm between largest and smallest pipe length giving good results. The source characteristics were at least above 1000 RPM stable enough as to not significantly change the sound pressure level at the outlet. / För att kunna modellera ljudtrycket som avges från ett avgassystem behöver man kunna beskriva källan. Källan i form av en bränslemotor kan linjärt beskrivas som en källstyrka och en källimpedans. En bränslemotor kan dock ha en akustisk ickelinjär del vilket medför att källan kan vara beroende utav vilken last i form av ljuddämpare den är kopplad till. Första delen av detta arbete undersöker genom motorsimuleringar i GT-Power hur lasten påverkar källkarakteristiken. Den andra delen av arbetet kombinerar källkarakteristiken med simuleringar av ljuddämparen och jämför olika metoder för att få ljudtrycket vid utloppet av avgassystemet. Den första metoden för detta är direkt simulering av ljuddämparen i COMSOL Multiphysics där källkarakteristiken inkluderas och den andra metoden är transfermatris baserad. Det testas också hur känsligt ljudtrycket vid utloppet av ljuddämparen är för variationer i impedansen. För källkarakteristiken används fem laster per uträkning och slutsatsen dras att lasten i form av röret mellan motor och ljuddämpare samt ljuddämparen bör vara så lik som möjligt det riktiga systemet. Utöver det dras slutsatsen att en liten variation i det kopplande rörets längd ger bättre resultat och att en variation mellan största och minsta röret på 100 mm ger bra resultat. Till sist dras slutsatsen att för varvtal över 1000 RPM är källkarakteristiken tillräckligt stabil för att ge stabila resultat vid utloppet av ljuddämparen, medans under 1000 RPM kan det vara stabilt nog men här är validering viktigare.

A number of experimental and theoretical studies, performed in the field of technical flow duct acoustics are presented in this thesis. The acoustical methods treated are implemented on turbocharged IC-engines and engine gas exchange system components. A new method based on the well-known two-load technique has been developed. The method was applied to characterise the source data of various piston-engines with non-linear behaviour including a 6 cylinder turbo-charged truck diesel engine. The source characterisation results were compared to the results obtained using the linear two-load technique. It was demonstrated that the new non-linear multi-load technique gives improved results when the source is slightly non-linear. The use of active one-port models has been tested to characterize an air terminal device (ATD) as a source of flow generated noise. In order to predict the noise generation at different operating points of the device a scaling law was derived and verified. In the experimentally derived scaling law a flow speed dependence of 3 was found for the narrow band spectra, corresponding to a dipole-like behavior of the source in the plane wave range. The proposed technique was validated successfully and the results indicated a good prediction of in-duct sound generation by the air terminal device. Sound reflection from hot flow duct openings has been investigated experimentally. The reflection coefficient was measured for flow temperatures up to 500 ºC and jet velocities up to 108m/s. The results have been compared with famous Munt’s theory. It was concluded that at low Mach number and Helmholz number cases the results agree well with the Munt’s model. This was the first experimental validation of the theory for hot flow conditions. Experimental procedures to determine the sound transmission through automotive turbo-charger compressors were developed and described in detail. An overview of a unique turbocharger testing facility established at KTH CICERO in Stockholm is given. The facility can be used to measure acoustic two-port data for turbo-compressors. Results from measurements on a passenger car turbo-compressor are presented and the influence of operating conditions on the sound transmission is discussed. Current wave action models developed in CMT for computation of the gas exchange processes in I.C. engines have been implemented to determine the acoustic wave transmission through the turbo- compressor. The models are validated with the experimental data and the results are presented for different operating conditions of a Volvo passenger car turbo-compressor. / QC 20100809

<p>Intake and Exhaust system noise makes a huge contribution to the interior and exterior noise of automobiles. There are a number of linear acoustic tools developed by institutions and industries to predict the acoustic properties of intake and exhaust systems. The present project discusses and validates, through measurements, the proper modelling of these systems using BOOST-SID and discusses the ideas to properly convert a geometrical model of an exhaust muffler to an acoustic model. The various elements and their properties are also discussed.</p><p>When it comes to Acoustic properties there are several parameters that describe the performance of a muffler, the Transmission Loss (TL) can be useful to check the validity of a mathematical model but when we want to predict the actual acoustic behavior of a component after it is installed in a system and subjected to operating conditions then we have to determine other properties like Attenuation, Insertion loss etc,.</p><p>Zero flow and Mean flow (M=0.12) measurements of these properties were carried out for mufflers ranging from simple expansion chambers to complex geometry using two approaches 1) Two Load technique 2) Two Source location technique. For both these cases, the measured transmission losses were compared to those obtained from BOOST-SID models.</p><p>The measured acoustic properties compared well with the simulated model for almost all the cases.</p>

Intake and Exhaust system noise makes a huge contribution to the interior and exterior noise of automobiles. There are a number of linear acoustic tools developed by institutions and industries to predict the acoustic properties of intake and exhaust systems. The present project discusses and validates, through measurements, the proper modelling of these systems using BOOST-SID and discusses the ideas to properly convert a geometrical model of an exhaust muffler to an acoustic model. The various elements and their properties are also discussed. When it comes to Acoustic properties there are several parameters that describe the performance of a muffler, the Transmission Loss (TL) can be useful to check the validity of a mathematical model but when we want to predict the actual acoustic behavior of a component after it is installed in a system and subjected to operating conditions then we have to determine other properties like Attenuation, Insertion loss etc,. Zero flow and Mean flow (M=0.12) measurements of these properties were carried out for mufflers ranging from simple expansion chambers to complex geometry using two approaches 1) Two Load technique 2) Two Source location technique. For both these cases, the measured transmission losses were compared to those obtained from BOOST-SID models. The measured acoustic properties compared well with the simulated model for almost all the cases.

Цель исследования – изучить развития торговой деятельности Китая с Россией и европейскими странами в рамках внешнеторговой политики, проводимой правителями Цинской империи в разные периоды. Объект данного исследования – торгово-экономические отношения Китая с Россией и Европой в 1722-1820 гг. Предмет исследования – торговая деятельность Китая с Европой и Россией и политика экономического развития, проводимая цинским правительством в указанный хронологический период. Представленная магистерская диссертация состоит из введения, трех глав, заключения, списка используемых источников и литературы, приложений. В первой главе рассматривается развитие межгосударственных торговых контактов Китая с Европой и Россией в эру Юнчжэн. Во второй главе исследуется этап активизации русско-китайских торговых отношений на Севере Китая в Кяхте и становление особой системы монопольной торговли с иностранцами в Гуанчжоу в эру Цяньлун. В третьей главе проанализированы особенности торговли на территории Кяхты и Гуанчжоу при императоре Цзяцине. В заключении приводятся краткие выводы по проведенным исследованиям. / The aim of the study is to examine the development of China's trade activities with Russia and European countries within the foreign trade policy pursued by the rulers of the Qing Empire in different periods. The object of this study is trade and economic relations of China with Russia and Europe. Subject of the research is China's trade activities with Europe and Russia and economic development policies pursued by the Qing government in the specified chronological period. This master's thesis consists of an introduction, three chapters, a conclusion, a list of used sources and literature, and appendices. The first chapter examines the development of China's interstate trade contacts with Europe and Russia in the Yongzheng era. The second chapter examines the stage of activation of the Russian-Chinese trade relations in the North China and formation of the special monopoly trade system with foreigners in Guangzhou in the Qianlong era. The third chapter analyses peculiarities of trade in the territories of Kyakhta and Guangzhou under the Jiaqing Emperor. The conclusion concludes with brief conclusions of the research.