Sökning: "acoustic analysis"

Visar resultat 16 - 20 av 234 avhandlingar innehållade orden acoustic analysis.

  1. 16. Numerical Methods for Aeroacoustic Analysis of Turbomachinery

    Författare :Daniel Lindblad; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Convective Ffowcs Williams - Hawkings Equation; Computational Aeroacoustics; Acoustic Analogy; Von Neumann Stability Analysis; Tonal Noise; CAA; Harmonic Balance Method; Counter Rotating Open Rotor;

    Sammanfattning : Air transportation is today an integral part of many peoples life and it continuously grow to serve more of us in new and ingenious ways. There are however negative sides to this growth as well, such as increased noise around airports and more CO2 emissions, which must be addressed if aviation is to be part of a sustainable future. LÄS MER

  3. 17. Numerical Techniques for Acoustic Modelling and Design of Brass Wind Instruments

    Författare :Daniel Noreland; Bertil Gustafsson; Leif Abrahamsson; Björn Sjögreen; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Acoustic horn; brass wind instrument; loudspeaker; optimization; hybrid method; Numerical Analysis; Numerisk analys;

    Sammanfattning : Acoustic horns are used in musical instruments and loudspeakers in order to provide an impedance match between an acoustic source and the surrounding air. The aim of this study is to develop numerical tools for the analysis and optimisation of such horns, with respect to their input impedance spectra. LÄS MER

  4. 18. Assessing precision and accuracy in acoustic scattering matrix measurements

    Författare :Luck Peerlings; Hans Bodén; Susann Boij; Avraham Hirschberg; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; aero-acoustics; sudden area expansion; in-duct acoustics; acoustic scattering matrix; impedance tube; uncertainty analysis; systematic errors; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : Acoustic scattering matrices are used to characterize the influence of inline duct elements on the acoustic wave propagation in wave guides.When measuring the properties of these matrices, errors are always present in the results and need to be characterized to make valid statements on the correspondence between model predictions and measurements. LÄS MER

  5. 19. Analysis of Acoustic Absorption with Extended Liner Reaction and Grazing Flow

    Författare :Anna Färm; Mats Åbom; Lars Enghardt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound absorption; acoustic lining; non-locally reacting; boundary layer; grazing flow; sound field; transfer matrix method;

    Sammanfattning : Acoustic absorbing liners are efficient and commonly used measures to reduce sound levels in many fields of application. The sound reducingperformance of the liners is dependent on the acoustic state, defined by e.g. the flow and sound field interacting with the liner. LÄS MER

  7. 20. Spectral properties of elliptic operators in singular settings and applications

    Författare :Medet Nursultanov; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : The present thesis is focused on the investigation of the spectral properties of the linear elliptic operators in the presence of singularities. It is divided into three chapters. In the first chapter, we consider geometric singularities. LÄS MER