Download or read book Secondary Instabilities of G rtler Vortices in High Speed Boundary Layers written by Jie Ren and published by Springer. This book was released on 2017-10-27 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis first reveals the mechanism of Görtler instabilities and then demonstrates how transitions at hypersonic flows can be effectively controlled (either promoted or suppressed) with Görtler or Klebanoff modes. It focuses on understanding and controlling flow transitions from mild laminar to fully turbulent flows at high speeds—aspects that have become crucial at the dawn of an incredible era, in which hypersonic vehicles are becoming available. Once this occurs, it will be possible to travel from Beijing to Los Angeles within just 2 hours, and we will all live in a genuinely global village—and not just virtually, but physically. Görtler instabilities have often been used to promote flow transition in hypersonic vehicles. However, how Görtler instabilities are excited and how they evolve in hypersonic flows are questions that have yet to be answered.

Download or read book Control of G rtler Vortices in High speed Boundary Layers written by Radwa Alaziz and published by . This book was released on 2017 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Görtler vortices develop in boundary layer flows over concave surfaces due to the imbalance between centrifugal forces and the wall-normal pressure gradient. These vortices can be efficient precursors to transition in boundary layers exposed to freestream disturbance or surface non-uniformities, because they can alter the mean flow causing the laminar flow to breakdown into turbulence. In this thesis, a control technique aimed at reducing the energy associated with Görtler vortices that develop in supersonic boundary layers is introduced and tested. The control algorithm is based on distributed blowing and suction, with sensors placed either in the flow or at the wall. The result show that there is a dependence between the efficiency of the control algorithm and the spanwise separation of the vortices, that is the energy reduction is more significant for larger spanwise separations. The efficiency of the control algorithm seems to be insensitive to the variation of the Mach number.

Download or read book On the Gortler Vortex Instability Mechanism at Hypersonic Speeds written by Philip Hall and published by . This book was released on 1989 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Control of G rtler Vortices by Means of Wall Deformations and Blowing suction written by Lamiae Taoudi and published by . This book was released on 2016 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Görtler vortices evolve in boundary layers over concave surfaces as a result of the imbalance between centrifugal forces and radial pressure gradients. Depending on various geometrical and free-stream flow conditions, these instabilities may lead to secondary instabilities and early transition to turbulence. In this thesis, a control algorithm based on the boundary region equations is applied to reduce the strength of the Görtler instabilities by controlling the energy of the fully developed vortices, using either local wall deformations or blowing/suction at the wall. A proportional-integral control scheme is utilized to deform the wall or to provide transpiration velocity, where the inputs are either the wall-normal or streamwise velocity components in a plane that is parallel to the wall. The results show that the control based on wall deformation using wall-normal velocity components is more effective in tempering the vortex during its streamwise growth by almost one or two orders of magnitude.

Download or read book The Growth of Goertler Vortices in Compressible Boundary Layers written by and published by . This book was released on 1987 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Fully Nonlinear Development of G rtler Vortices in Growing Boundary Layers written by Philip Hall and published by . This book was released on 1987 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Goertler Vortex Instability Mechanism in Three dimensional Boundary Layers written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1984 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vortex Instabilities in 3D Boundary Layers The Relationship Between Goertler and Crossflow Vortices written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1990 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stability of Gortler Vortices in Boundary Layers written by George Chi-Fung Ng and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Nonlinear Development of Gortler Vortices in Growing Boundary Layers written by Philip Hall and published by . This book was released on 1986 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The G rtler Vortex Instability Mechanism in Three dimensional Boundary Layers written by Philip Hall and published by . This book was released on 1984 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Growth of G rtler Vortices in Compressible Boundary Layers written by Philip Hall and published by . This book was released on 1987 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Visualization written by Alexander J. Smits and published by World Scientific. This book was released on 2012 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the 2nd edition of the book, Flow Visualization: Techniques and Examples, which was published by Imperial College Press in 2000. Many of the chapters have been revised and updated to take into consideration recent changes in a number of flow visualization and measurement techniques, including an updated high quality flow gallery. Unique among similar publications, this book focuses on the practical rather than theoretical aspects. Obtaining high quality flow visualization results is, in many ways, more of an art than a science, and experience plays a key deciding role. The depth and breadth of the material will make this book invaluable to readers of all levels of experience in the field.

Download or read book Shock Wave Boundary Layer Interactions written by Holger Babinsky and published by Cambridge University Press. This book was released on 2011-09-12 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock wave-boundary-layer interaction (SBLI) is a fundamental phenomenon in gas dynamics that is observed in many practical situations, ranging from transonic aircraft wings to hypersonic vehicles and engines. SBLIs have the potential to pose serious problems in a flowfield; hence they often prove to be a critical - or even design limiting - issue for many aerospace applications. This is the first book devoted solely to a comprehensive, state-of-the-art explanation of this phenomenon. It includes a description of the basic fluid mechanics of SBLIs plus contributions from leading international experts who share their insight into their physics and the impact they have in practical flow situations. This book is for practitioners and graduate students in aerodynamics who wish to familiarize themselves with all aspects of SBLI flows. It is a valuable resource for specialists because it compiles experimental, computational and theoretical knowledge in one place.

Download or read book Effects of Goertler Vortices Wall Cooling and Gas Dissociation on the Rayleigh Instability in a Hypersonic Boundary Layer written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1991 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Nonlinear Development of Gortler Vortices in Frowing Boundary Layers written by Philip Hall and published by . This book was released on 1986 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Discharges for High Speed Boundary Layer Control Postprint written by and published by . This book was released on 2006 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface plasma discharges have been shown to be effective in altering laminar boundary layers, Judicious choice of electrode shape can create a discharge that emulates a wedge or a bump, The "virtual wedge" discharge has been shown to create a local pressure rise with potential applications to vehicle control. The "virtual bump" creates a lesser pressure rise, but strong distortion of the boundary layer. In the current work the effect of the bump discharge on laminar shock boundary layer interactions is explored. Laminar shock boundary layer interactions are created with an impinging shock on a flat plate at a freestream Mach number of 5. The primary instrumentation is a low-modulus elastomer doped with a pressure-sensitive dye, Intensity distributions from the dye are imaged to interrogate the surface pressure. Displacement of surface markers provides surface shear information. Results show the presence of Gortler vortices in the reattaching shear flow. The Gortler vortices are also evident in temperature-sensitive paint images.