Search for dissertations about: "Mach number"

Showing result 1 - 5 of 54 swedish dissertations containing the words Mach number.

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

   Author : Andreas Holmberg; Hans Bodén; Lars Enghardt; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; 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

4. 2. Modeling of sound-turbulence interaction in low-Mach-number duct flows

   Author : Chenyang Weng; Mats Åbom; Susann Boij; Avraham Hirschberg; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Järnvägsgruppen - Ljud och vibrationer; Järnvägsgruppen - Ljud och vibrationer;

   Abstract : When sound waves propagate in a duct in the presence of turbulent flow, tur- bulent mixing can cause extra attenuation of the sound waves in addition to that caused by the viscothermal eects. Experiments show that compared to the vis- cothermal eects, turbulent absorption becomes the dominant contribution to the sound attenuation at suciently low frequencies. READ MORE

5. 3. Theoretical and numerical studies of sound propagation in low-Mach-number duct flows

   Author : Chenyang Weng; Mats Åbom; Susann Boij; Ardeshir Hanifi; Anurag Agarwal; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeroacoustics; Acoustic wave absorption; Acoustic wave propagation; Boundary layer turbulence; DNS; Engineering Mechanics; Teknisk mekanik;

   Abstract : When sound waves propagate in a duct in the presence of turbulent flow, turbulent mixing can cause attenuation of the sound waves extra to that caused by the viscothermal effects. Experiments show that compared to the viscothermal effects, this turbulent absorption becomes the dominant contribution to the sound attenuation at sufficiently low frequencies. READ MORE

6. 4. Frequency Domain Linearized Navier-Stokes Equations Methods for Low Mach Number Internal Aeroacoustics

   Author : Axel Kierkegaard; Gunill Efraimsson; Christophe Schram; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Acoustics; Akustik;

   Abstract : Traffic is a major source of environmental noise in modern day's society. As a result, the development of new vehicles are subject to heavy governmental legislations. The major noise sources on common road vehicles are engine noise, transmission noise, tire noise and, at high speeds, wind noise. READ MORE

7. 5. Predictions of Aerodynamically Induced Wind Noise Around Ground Vehicles

   Author : Jonas Ask; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; side mirror; LES; incompressibility; Curle; CAA; air rush noise; low Mach number; ground vehicle; cavity;

   Abstract : Over the last decade wind noise has with few exceptions consistently generated a constant or even growing level of customer complaints to automotive companies world-wide. This can partly be explained by a relatively greater focus on engine, power-train and tire noise combined with a growing need to reduce weight in future cars. READ MORE