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Book Boundary Layers Induced by Three Dimensional Vortex Loops

Download or read book Boundary Layers Induced by Three Dimensional Vortex Loops written by and published by . This book was released on 1993 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow field generated by a helicopter in flight is extremely complex and it has been recognized that interactions between different components can significantly affect helicopter performance. In particular, the effects of the interaction between the rotor wake and the helicopter fuselage are extremely difficult to predict and pose a challenging problem for researchers and designers in the rotorcraft area. In the present work, a model for the interaction of a rotor-tip-vortex with the airframe of a helicopter is developed. The present report describes the calculation of the motion of the tip-vortex toward the airframe, the calculation of the induced pressure on the airframe, and the calculation of the boundary-layer flow under the vortex during the time period prior to the time when a portion of the tip-vortex collides with the airframe.

Book The Viscous Flow Induced Near a Wall by Counter rotating Vortex Pairs and Vortex Loops

Download or read book The Viscous Flow Induced Near a Wall by Counter rotating Vortex Pairs and Vortex Loops written by Seyham Ersoy and published by . This book was released on 19?? with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vortex motion above walls is observed in a variety of physical situations this study the problem of how a viscous flow near a wall responds to the motion of certain vortex motions. Specifically the unsteady boundary layers induced by the motion of two dimensional rectilinear vortex pairs and three dimesional vortex loops in an otherwise stagnant fluid above a plane wall are considered; numerical solutions are obtained for the evolution of the boundary layer flow as it develops under the influence of the moving vortices. All of the vortex flows considered in this study are related to more complex vortex flows observed in a diverse variety of physical situations; many of these situations relate to the observed time-dependent flow in a turbulent boundary layer and are discussed. The boundary layer induced by a pair of counter rotating rectilinear vortices in motion above a plane in an otherwise stagnant fluid is addressed; depending on the assumed sense of rotation the vortices either move toward or recede from the wall. A symmetric situation is considered where both vortices are equidistant from the wall. An symmetric situation is considered where a counter rotating pair approaches the wall at angle of attack. The motion of three-dimensional vortex loops which have a plane of symmetry is considered. A method is developed which allows the computation of the flow velocities on and near the symmetry plane of the loop. The computed results show a variety of complex three dimensional separation phenomena; again the boundary layer solutions ultimately show strong localized growth and are suggestive that a boundary-layer eruption and strong viscous-inviscid interaction will occur.

Book Three dimensional Vortex body Interaction in a Viscous Fluid

Download or read book Three dimensional Vortex body Interaction in a Viscous Fluid written by Jeffrey S. Marshall and published by . This book was released on 1999 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and computational study of the impact of a vortex with a body oriented normal to the vortex axis was performed. Particular focus was placed on understanding characteristics of the secondary vorticity ejected from the body and the interaction of the secondary vorticity with the primary vortex. Since both onset of boundary layer separation and the form of the secondary vorticity structures are sensitive to variation of the velocity normal to the body axis, the effect of normal velocity on vortex-body interaction was carefully examined. The physical features of the flow evolution were categorized in terms of an impact parameter and a thickness parameter, which respectively represent ratios of velocity and length scales associated with the vortex to those associated with the flow in the absence of the vortex. Experiments were performed using a combination of laser-induced fluorescence (LIF) flow visualization and particle-image velocimetry (PIV) in a water tank to examine the form of the secondary vorticity structures with both "high" and "low" values of the impact parameter for normal vortex interaction with a circular cylinder and with a thin blade. A new type of Lagrangian vorticity method based on a tetrahedral mesh was developed and applied to compute the secondary vorticity evolution during vortex-cylinder interaction. Computations were also performed for model problems to examine in detail wrapping of a vortex loop around a columnar vortex and impulsive cutting of a columnar vortex with finite axial flow.

Book Vortex Loop Dynamics a Phenomenological Model for Turbulent Boundary Layer Structure

Download or read book Vortex Loop Dynamics a Phenomenological Model for Turbulent Boundary Layer Structure written by Thomas L. Doligalski and published by . This book was released on 1986 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a combined analytic/experimental study of the unsteady development of three dimensional vortex loops in the vicinity of solid surfaces and under the influence of a crossflow is detailed. It is important to understand the factors which influenced the development of this coherent structure, since it has long been recognized that a three-dimensional convecting stretching vortex loop is a major component of turbulent boundary layer flow. The initial development of this structure is examined by numerically and experimentally studying the temporal and spatial interaction between a two dimensional viscous jet and a viscous crossflow. In the cases considered the crossflow caused the ejected fluid from the jet to be rolled up into a vortex structure which appeared to be similar to the loop-like coherent vortex structure found in turbulent boundary layers. To study the long time development of vortex loops, a combined numeric and experimental approach is again used. These synergistic studies indicate that substantial loop growth occurs only due to the presence of an imposed shear, such as that experienced by the loop within the turbulent boundary layer. This interaction between the loop and the imposed crossflow plays the dominant role in the loop deformation process.

Book Three Dimensional Vortex Interactions in Turbulent Boundary Layers

Download or read book Three Dimensional Vortex Interactions in Turbulent Boundary Layers written by C. R. Smith and published by . This book was released on 1985 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combined analytical experimental program, which has as its continuing objective the detailed investigation of the three dimensional vortex interactions which take place in turbulent boundary layers, is described and the accomplishments detailed. The analytical and numerical studies have examined both the development and characteristics of loop and hairpin vortices in both uniform and shear flows; particular attention has been paid to the strong three dimensional, inviscid viscous interaction of these types of vortical flow structures with wall region fluid. The experimental studies have focussed on the creation & detailed examination of three dimensional hairpin vortices, developing flow visualization patterns for cross-comparison with both the analytical studies and fully turbulent boundary layer flows. A technique for developing quantitative data by image processing of the visualization patterns is also described. Keywords: Turbulent boundary layer; Coherent structure; Flow visualization; Numerical modelling; Vortex wall interactions; Computer aided analysis; Loop vortices; Hairpin vortices.

Book Legislazione e controllo igienico del latte in Svizzera

Download or read book Legislazione e controllo igienico del latte in Svizzera written by and published by . This book was released on 1969 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Inviscid Vortex Motions in Weakly Three dimensional Boundary Layers and Their Relation with Instabilities in Stratified Shear Flows

Download or read book Inviscid Vortex Motions in Weakly Three dimensional Boundary Layers and Their Relation with Instabilities in Stratified Shear Flows written by Institute for Computer Applications in Science and Engineering and published by . This book was released on 1992 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Three dimensional Turbulent Boundary Layers

Download or read book Three dimensional Turbulent Boundary Layers written by O. Sendstad and published by . This book was released on 1992 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Three dimensional Boundary Layer Flow Due to a Rotor Tip Vortex

Download or read book The Three dimensional Boundary Layer Flow Due to a Rotor Tip Vortex written by H. Affes and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book On the Stability of Three Dimensional Boundary Layers

Download or read book On the Stability of Three Dimensional Boundary Layers written by Erik Janke and published by . This book was released on 1999 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Research in Progress

Download or read book Research in Progress written by and published by . This book was released on 1992 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: