Search for dissertations about: "micro-perforated"

Found 4 swedish dissertations containing the word micro-perforated.

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. Studies of sound generation and propagation in flow ducts

   Author : Fabrice Ducret; Mats Åbom; Andy Moorhouse; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; two-port; plane wave; HVAC system; tailpipe; exhaust system; flexible duct; pipe; reflection coefficient; impedance; flow noise; vorticity; damping; scaling laws; impedance; transmission loss; perforated plate; slit; non linearity; Acoustics; Akustik;

   Abstract : This thesis contains three papers investigating problems of interest for noise control in ducts. The first part of this thesis treats the sound propagation in rectangular ducts with flexible walls. Various experimental techniques are performed to measure the internal sound propagation and radiation to the surrounding. READ MORE

5. 3. Experimental and Numerical Multi-port Eduction for Duct Acoustics

   Author : Stefan Sack; Abom Mats; Phillip Joseph; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustics; aeroacoustics; flowacoustics; multi-ports; orifice; silencer; experiment; numeric; IDDES; LNSE; optimization; test rig; Monte Carlo; Teknisk mekanik; Engineering Mechanics;

   Abstract : Sound generation and propagation in circular ducts for frequencies beyond the cut-on frequencies of several higher order acoustic modes is investigated. To achieve this, experimental and numerical set-ups are designed and used to research aeroacoustic interactions between in-duct components and to conceive noise mitigation strategies. READ MORE

6. 4. Production and application of fine fractions made of chemical pulp for enhanced paperboard strength

   Author : Elisabeth Björk; Per Engstrand; Mark Martinez; Mittuniversitetet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Abstract : For all kinds of paperboard packages, the bending stiffness of the paperboard is a crucial property. In multi-ply folding boxboard (FBB) grades, this is obtained by placing different stocks in the outer and centre plies of the board. In the outer plies, a stock with a high tensile stiffness is used, typically made from refined kraft pulp fibres. READ MORE