Sökning: "fluid shifts"

Visar resultat 1 - 5 av 21 avhandlingar innehållade orden fluid shifts.

1. 1. Transitional flow in ordered porous media

   Författare :Tobias Forslund; Staffan Lundström; Sofia Larsson; Gunnar Hellström; Krishna Pillai; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Porous media; Lattice Boltzmann Method; GPU Programming; Tomographic PIV; Laser Doppler Velocimetry; Strömningslära; Fluid Mechanics;

   Sammanfattning : Porous media, here defined as any permeable structure allowing a fluid to flow through, are relevant to a multitude of engineering applications and natural processes. The observed macroscopic properties of the porous media such as mixing, heat transfer and apparent permeability are properties which are affected by the flow and especially the type of flow, or flow region. LÄS MER

3. 2. Transition in Particle-laden Flows

   Författare :Joy Klinkenberg; Luca Brandt; Shuisheng He; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transition; modal analysis; non-modal analysis; multi-phase flow; particle-laden; heavy particles; light particles;

   Sammanfattning : This thesis presents the study of laminar to turbulent transition of particle laden flows. When a flow becomes turbulent, the drag increases one order of magnitude compared to a laminar flow, therefore, much research is devoted to understand and influence the transition. LÄS MER

4. 3. Reduction of Audible Noise of a Traction Motor at PWM Operation

   Författare :Hanna Amlinger; Ines Lopez Arteaga; Siv Leth; Wolfgang Kropp; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; electromagnetic noise; pulse width modulation PWM ; switching frequency; traction motor; Vehicle and Maritime Engineering; Farkostteknik;

   Sammanfattning : A dominating source for the radiated acoustic noise from a train at low speeds is the traction motor. This noise originates from electromagnetic forces acting on the structure resulting in vibrations on the surface and thus radiated noise. It is often perceived as annoying due to its tonal nature. LÄS MER

5. 4. Transition to turbulence in the asymptotic suction boundary layer

   Författare :Taras Khapko; Dan Henningson; Philipp Schlatter; Yohann Duguet; Marc Avila; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; boundary layers; instability; laminar-turbulent transition; dynamical systems; edge states; near-wall turbulence; laminarisation;

   Sammanfattning : The focus of this thesis is on the numerical study of subcritical transition to turbulence in the asymptotic suction boundary layer (ASBL). Applying constant homogeneous suction prevents the spatial growth of the boundary layer, granting access to the asymptotic dynamics. LÄS MER

7. 5. Stability and transition on wind turbine blades

   Författare :Thales Coelho Leite Fava; Ardeshir Hanifi; Dan Henningson; Stefania Cherubini; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Boundary layer stability; free-stream turbulence; laminar-turbulent transition; low-frequency oscillations; rotation effects; wind turbine blades.; Gränsskiktsstabilitet; friströmsturbulens; laminär-turbulent omslag; lågfrekventa svängningar; rotationseffekter; vindkraftverksblad.; Teknisk mekanik; Engineering Mechanics;

   Sammanfattning : Transition on wind turbine blades is a highly complex phenomenon due to the myriad effects influencing the process. This thesis studies some of them, namely free-stream turbulence (FST), rotation, and three-dimensionality. The investigations employ large eddy simulations (LES) with and without (implicit or wall-resolved LES) a subgrid-scale model. LÄS MER