Search for dissertations about: "ducts"

Showing result 1 - 5 of 102 swedish dissertations containing the word ducts.

  1. 1. Innovative noise control in ducts

    Author : Maaz Farooqui; Mats Åbom; Hans Bodén; Tamer Elnady; Jeong-Guon Ih; KTH; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Locally resonant materials; slow sound; acoustic impedance; metallic foam; low frequency noise; mufflers; lined ducts; grazing flow; flow duct; impedance eduction.; Farkostteknik; Vehicle and Maritime Engineering;

    Abstract : The objective of this doctoral thesis is to study three different innovative noise control techniques in ducts namely: acoustic metamaterials, porous absorbers and microperforates. There has been a lot of research done on all these three topics in the context of duct acoustics. READ MORE

  2. 2. Aerodynamic Design and Optimization of Intermediate Ducts for High By-pass Ratio Jet Engines

    Author : Fredrik Wallin; Chalmers University of Technology; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Intermediate transition ducts; vortex generators; S-shaped ducts; response surface methodology; source term model; optimization;

    Abstract : Demands on improved efficiency and reduced noise levels cause a strive toward high by-pass ratio commercial aero engines. This results in multi-spool aero engines with small high-pressure ratio cores and large fans. The low-pressure system has a lower rotational speed and a larger radius than the high-pressure core system. READ MORE

  3. 3. Modelling and Characterization of Perforates in Lined Ducts and Mufflers

    Author : Tamer Elnady; KTH; []
    Keywords : Perforates; Liners; Acoustic impedance; Hot stream liners; Hard splices; Mufflers; Lined ducts; Collocation; Flow duct.;

    Abstract : Increased national and international travel over the lastdecades has caused an increase in the global number ofpassengers using different means of transportation. Greateffort is being directed to improving the noisy environment inthe residential community. READ MORE

  4. 4. Experimental Determination of Aeracoustic Sources in Low Mach Number Internal Flows

    Author : Andreas Holmberg; Hans Bodén; Lars Enghardt; KTH; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeracoustics; ducts; N-ports; scattering matrix; wave decomposition; source determination; over-determination; flow noise; fluid-acoustic interaction; fluid-structure-acoustic interaction; wave number; T-junction; power balance; grazing-bias flow; Acoustics; Akustik; Vehicle engineering; Farkostteknik;

    Abstract : In this thesis, the in-duct experimental methods for determining aeroacoustic N-ports of in-duct elements are discussed and improved. The scattering matrix determination methods and the related wave decomposition methods are evaluated from measurements in an empty duct carrying a mean flow. READ MORE

  5. 5. Numerical Investigation of Turbulent Fluid Flow and Heat Transfer in Complex Ducts

    Author : Masoud Rokni; Värmeöverföring; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SED; WET; GGDH; RNG; RSM; EASM; Low-Reynolds; Non-linear k-e; Heat transfer; Turbulent; Complex ducts; Secondary flows; Temperature invariance; Energy research; Energiforskning;

    Abstract : Th need for a reliable and reasonable accurate turbulence model without specific convergence problem for calculating duct flows in industrial applications has become more evident. In this study a general computational method has been developed for calculating turbulent quantities in any arbitrary three dimensional duct. READ MORE