Advanced search

Showing result 1 - 5 of 9 swedish dissertations matching the above criteria.

2. 1. Investigation of perforated mufflers and plates

   Author : Ying Guo; Mast Abom; Ragnar Glav; KTH; []
   Keywords : sound; perforated; micro-perforated; muffler; flow; hole; impedance; model; experiment;

   Abstract :     Mufflers are used in for instance exhaust system of cars or trucks to reduce noise. Perforated pipes are one of the main components of modern mufflers. To study acoustic properties of mufflers with perforated pipe is one of the main targets of this thesis. READ MORE

4. 2. Acoustic source characterisation for non-linear in-duct sources

   Author : Fredrik Albertson; KTH; []
   Keywords : in-duct source; source characterisation; non-linear source; linearity test; hybrid method; IC-engine; muffler; coupling method;

   Abstract : Different ways to model acoustic in-duct sources have beenanalysed. Measurements were conducted on two diesel truckengines. It was found that for steady state oscillations, onecould linearise in the neighbourhood of a given linearisationpoint, i.e. READ MORE

5. 3. Aeroacoustics Studies of Duct Branches with Application to Silencers

   Author : Mikael Karlsson; Mats Åbom; Luc Mongeau; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; silencer; muffler; confined flows; flow duct; aeroacoustics; vortex sound; acoustic multiports; linear stability; self-sustained oscillations; whistling; Herschel-Quincke tube; acoustic resonator; Fluid mechanics; Strömningsmekanik;

   Abstract : New methodologies and concepts for developing compact and energy efficient automotive exhaust systems have been studied. This originates in the growing concern for global warming, to which road transportation is a major contributor. READ MORE

6. 4. Investigation and Optimization of the Acoustic Performance of Exhaust Systems

   Author : Sara Elsaadany; Mats Åbom; Ray Kirby; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Exhaust systems; noise; pressure drop; 1D models; perforated mufflers; after treatment devices; optimization;

   Abstract : 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. READ MORE

7. 5. Analysis, Control, and Design Optimization of Engineering Mechanics Systems

   Author : Esubalewe Lakie Yedeg; Martin Berggren; Eddie Wadbro; Anton Evgrafov; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Topology optimization; Helmholtz equation; acoustic impedance; anisotropic filter; thin structures; finite element method; Nitsche-type method; interface problem; Optimal control; adjoint method; business data processing; administrativ databehandling;

   Abstract : This thesis considers applications of gradient-based optimization algorithms to the design and control of some mechanics systems. The material distribution approach to topology optimization is applied to design two different acoustic devices, a reactive muffler and an acoustic horn, and optimization is used to control a ball pitching robot. READ MORE