Sökning: "leading-edge effects"

Visar resultat 1 - 5 av 21 avhandlingar innehållade orden leading-edge effects.

1. 1. Investigations of Heat Transfer and Fluid Flow in the Pocket Region of a Gas Turbine Engine and Cooling of a Turbine Blade

   Författare :Jian Liu; Värmeöverföring; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; pocket cavity; symmetric vane; Liquid Crystal Thermography; truncated ribs; staggered arrangement; perforated ribs; secondary flows; endwall film cooling; leading edge; turbine vane; coolant coverage;

   Sammanfattning : In the present work, heat transfer within gas turbine applications are investigated bothexperimentally and numerically. The main content concerns heat transfer and fluidflow over the pocket region and cooling of a turbine blade. LÄS MER

3. 2. Receptivity of Boundary-Layer Flows over Flat and Curved Walls

   Författare :Lars-Uve Schrader; Luca Brandt; Dan Stefan Henningson; Gregoire Casalis; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Boundary-layer receptivity; laminar-turbulent transition; swept-plate boundary layer; Görtler flow; leading-edge effects; swept-wing flow; crossflow vortices; Görtler rolls; disturbance streaks; wall roughness; free-stream turbulence; Fluid mechanics; Strömningsmekanik;

   Sammanfattning : Direct numerical simulations of the receptivity and instability of boundary layers on flat and curved surfaces are herein reported. Various flow models are considered with the aim to capture aspects of flows over straight and swept wings such as wall curvature, pressure variations, leading-edge effects, streamline curvature and crossflow. LÄS MER

4. 3. Receptivity of Boundary Layers under Pressure Gradient

   Författare :Lars-Uve Schrader; Luca Brandt; Dan Henningson; Tamer Zaki; KTH; []
   Nyckelord :Leading-edge effects;

   Sammanfattning : Boundary-layer flow over bodies such as aircraft wings or turbine blades is characterized by a pressure gradient due to the curved surface of the body. The boundary layer may experience modal and non-modal instability, and the type of dominant instability depends on whether the body is swept with respect to the oncoming flow or not. LÄS MER

5. 4. 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

7. 5. Effects of Post-Glacial Range Expansions and Population Bottlenecks on Species Richness

   Författare :Anders Ödeen; Godfrey Hewitt; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; Peripatric speciation; bottlenecks; mating asymmetries; Kaneshiro model; Quaternary ice-ages; phylogeny; Motacilla; Motacilla flava; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; Animal Ecology; zooekologi;

   Sammanfattning : This thesis relates modern speciation theory to the effects of sudden changes in the range and size of populations. Special reference is made to the climatic oscillations during the Quaternary ice ages. LÄS MER