Sökning: "Hydrodynamic instability"

Visar resultat 1 - 5 av 20 avhandlingar innehållade orden Hydrodynamic instability.

1. 1. Numerical Study of Cellular Instability in Burner Stabilized Adiabatic Laminar Premixed Flames

   Författare :Jiangfei Yu; Strömningsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Detailed Numerical Simulation; Cellular premixed flame; Hydrogen; Oxy-fuel; Heat-flux burner; Hydrodynamic instability; Diffusive-thermal instability; Nonlinear flame dynamics.;

   Sammanfattning : The thesis deals with experiments and numerical simulations of adiabatic laminar premixed flames anchored to a heat-flux burner using different mixtures under various operating conditions. The aim is to obtain a better understanding of cellular instability in heat-flux burner anchored flames. LÄS MER

3. 2. Theoretical and Experimental Investigations of Nonlinear Flame Instability

   Författare :Li-Zheng Ma; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; nonlinear hydrodynamic instability; flame propagation and stretch effects; shock induced flame instability; tulip flame formation; interface tracking; the Schlieren technique; level set approach;

   Sammanfattning : Flame instability is both important and difficult to understand. Mechanisms of instability are complex, because instability often involves an interaction between several different physical phenomena, such as an unsteady chemical reaction, unsteady flame propagation generating an unsteady flow, acoustic waves or shock waves. LÄS MER

4. 3. The role of Landau-Darrieus instability in flame dynamics and deflagration-to-detonation transition

   Författare :Damir Valiev; Börje Johansson; Vladimir Karlin; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; flame; premixed; instability; front; Landau; Darrieus; fractal; freely; deflagration; detonation; transition; DDT; modeling; simulation; Other materials science; Övrig teknisk materialvetenskap;

   Sammanfattning : The role of intrinsic hydrodynamic instability of the premixed flame (known as Landau-Darrieus instability) in various flame phenomena is studied by means of direct numerical simulations of the complete system of hydrodynamic equations. Rigorous study of flame dynamics and effect of Landau-Darrieus instability is essential for all premixed combustion problems where multidimensional effects cannot be disregarded. LÄS MER

5. 4. Studies on instability and optimal forcing of incompressible flows

   Författare :Mattias Brynjell-Rahkola; Dan S. Henningson; Ardeshir Hanifi; Philipp Schlatter; François Gallaire; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; hydrodynamic stability; optimal forcing; resolvent operator; Laplace preconditioner; spectral element method; eigenvalue problems; inverse power method; direct numerical simulations; Falkner–Skan–Cooke boundary layer; localized roughness; crossflow vortices; Blasius boundary layer; localized suction; helical vortices; lid-driven cavity; cylinder flow; Teknisk mekanik; Engineering Mechanics;

   Sammanfattning : This thesis considers the hydrodynamic instability and optimal forcing of a number of incompressible flow cases. In the first part, the instabilities of three problems that are of great interest in energy and aerospace applications are studied, namely a Blasius boundary layer subject to localized wall-suction, a Falkner–Skan–Cooke boundary layer with a localized surface roughness, and a pair of helical vortices. LÄS MER

7. 5. Fronts and instabilities in laser ablation, organic semiconductors and quantum media

   Författare :Mikhail Modestov; Vitaly Bychkov; Mattias Marklund; Tito Mendonca; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; front; instability; deflagration; fysik; Physics;

   Sammanfattning : The concept of a front plays a decisive role in various elds in physics and beyond. In the present thesis we study key aspects of front dynamics and stability in the context of laser plasmas, organic semiconductors and quantum media. LÄS MER