Sökning: "Wave expansion method."

Visar resultat 1 - 5 av 33 avhandlingar innehållade orden Wave expansion method..

  1. 1. A Wave Expansion Method for Aeroacoustic Propagation

    Författare :Johan Hammar; Gunilla Efraimsson; Ciarán J. O'Reilly; Wim De Roeck; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound propagation; Sound generation; Aeroacoustics; Aerodynamics; Computational fluid dynamics; Computational aeroacoustics; Numerical methods; Lighthill; Curle; Ffowcs Williams and Hawkings; Frequency-domain propagation; Wave expansion method.; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : Although it is possible to directly solve an entire flow-acoustics problem in one computation, this approach remains prohibitively large in terms of the computational resource required for most practical applications. Aeroacoustic problems are therefore usually split into two parts; one consisting of the source computation and one of the source propagation. LÄS MER

  3. 2. Methods and techniques for precise and accurate in-duct aero-acoustic measurements : Application to the area expansion

    Författare :Luck Peerlings; Susann Boij; Hans Bodén; Yves Aurégan; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Area-expansion; Scattering matrix; Multi-microphone method; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : During the design and commissioning of combustion equipment, combustion associated instabilities are commonly encountered. These thermo-acoustic instabilities can cause undesirable noise, vibrations, local thermal and mechanical stresses in the combustor and are prominent in lean combustion. LÄS MER

  4. 3. Elastic Wave Scattering by Closed Cracks and Thin Flaws - Multiple Scattering and Resonances

    Författare :Arne S. Eriksson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SH-wave; evaluation of materials; direct integral equation; singularity expansion; ultrasonic testing;

    Sammanfattning : In this thesis we study elastic wave scattering by thin flaws and closed cracks, which finds applications in ultrasonic testing and evaluation of materials. First we consider the scattering of an SH-wave by a thin finite elastic layer between two elastic half-spaces. LÄS MER

  5. 4. Lung mechanics in the aging lung and in acute lung injury. Studies based on sinusoidal flow modulation

    Författare :Ulrika Bitzén; Lund Klinisk fysiologi; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Diagnostics; Diagnostik; acute lung injury; lung mechanics; acute respiratory distress syndrome; intensivvård; Anestesiologi; intensive care; Anaesthesiology; Andningsorganen; Respiratory system; Fysiologi; Physiology; flow regulation; method; lung resistance; compliance; aging;

    Sammanfattning : Knowledge about lung mechanics is of interest in intensive care to adjust mechanical ventilation and in the lung laboratory for diagnostics and evaluation of patients with various kinds of respiratory diseases. In mechanical ventilation a single inspiratory elastic pressure-volume (Pel/V) curve is difficult to interpret due to continuing re-expansion of collapsed lung units over a large pressure interval. LÄS MER

  7. 5. Prediction of random vibration using spectral methods

    Författare :Fredrik Birgersson; KTH; []
    Nyckelord :Spectral finite element method; distributed excitation; turbulent boundary layer measurements; random vibration; spectral super element method; wave expansion difference scheme; fluid-structure interaction;

    Sammanfattning : Much of the vibration in fast moving vehicles is caused bydistributed random excitation, such as turbulent flow and roadroughness. Piping systems transporting fast flowing fluid isanother example, where distributed random excitation will causeunwanted vibration. LÄS MER