Sökning: "Perforated plate"

Visar resultat 1 - 5 av 14 avhandlingar innehållade orden Perforated plate.

  1. 1. Studies of sound generation and propagation in flow ducts

    Författare :Fabrice Ducret; Mats Åbom; Andy Moorhouse; KTH; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  3. 2. Experimental Investigation of the Acoustic Properties of Perforate using Acoustic Three-Ports

    Författare :Shail A. Shah; Susann Boij; Hans Bodén; Wim De Roeck; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Duct Acoustics; Acoustical Three-port; Perforated plate; Transfer Impedance; Scattering Matrix; Grazing Flow; High-level Excitation; Non-linear effects; Flow-Acoustic Interaction; Rectangular T-Junction; Farkostteknik; Vehicle and Maritime Engineering;

    Sammanfattning : This thesis discusses the aero-acoustic characterisation of a perforate sample using a three-port technique. A rectangular T-junction with a flush mounted perforated sample at the intersection form the acoustical three-port. LÄS MER

  4. 3. Experimental and numerical study of the thermal and hydraulic effect of EMC screens in radio base stations : detailed and compact models

    Författare :Raúl Antón Remírez; Björn Palm; Masud Behnia; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sub-rack; perforated plate; air cooling; 90 degrees turn; flow deistribution; CFD; measurement; Mechanical energy engineering; Mekanisk energiteknik;

    Sammanfattning : Today’s telecommunication cabinets use Electro Magnetic Compliance (EMC) screens in order to reduce electromagnetic noise that can cause some miss functions in electronic equipment. Many radio base stations (RBSs) use a 90-degree building architecture: the flow inlet is perpendicular to the EMC screen, which creates a complex flow, with a 90-degree air turn, expansions, compressions, perforated plates and PCBs. LÄS MER

  5. 4. Frequency Domain Linearized Navier-Stokes Equations Methodology for Aero-Acoustic and Thermoacoustic Simulations

    Författare :Wei Na; Gunilla Efraimsson; Susann Boij; Martinez Lera Paula; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Linearized Navier-Stokes Equations; frequency domain; fluid equivalent model; hybrid liner; thermoacoustic instabilities; Rijke-tube; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The first part of the thesis focuses on developing a numerical methodology to simulate the acoustic properties of a hybrid liner consisting of a perforated plate, a porous layer and a Helmholtz cavity. Liners are always a standard way to reduce noise in today’s aeroengines, e.g. LÄS MER

  7. 5. Homogenization of pseudoparabolic reaction-diffusion-mechanics systems : Multiscale modeling, well-posedness and convergence rates

    Författare :Arthur J. Vromans; Adrian Muntean; Claudia Timofte; Karlstads universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Reaction-diffusion-mechanics system; parameter delimitation; parabolic-pseudoparabolic equations; weak solvability; Rothe method; periodic homogenization; corrector estimates; vanishing thin domains; Matematik; Mathematics;

    Sammanfattning : In this dissertation, parabolic-pseudoparabolic equations are proposed to couple chemical reactions, diffusion, flow and mechanics in heterogeneous materials using the framework of mixture theory. The weak solvability is obtained in a one dimensional setting for the full system posed in a homogeneous domain - a formulation which we have obtained using the classical mixture theory. LÄS MER