Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Consideration Of Unsteady Aerodynamics And Boundary Layer Transition In Rotorcraft Airfoil Design
Download Consideration Of Unsteady Aerodynamics And Boundary Layer Transition In Rotorcraft Airfoil Design full books in PDF, epub, and Kindle. Read online Consideration Of Unsteady Aerodynamics And Boundary Layer Transition In Rotorcraft Airfoil Design ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Consideration of Unsteady Aerodynamics and Boundary-Layer Transition in Rotorcraft Airfoil Design by : Bernardo Oliveira Vieira
Download or read book Consideration of Unsteady Aerodynamics and Boundary-Layer Transition in Rotorcraft Airfoil Design written by Bernardo Oliveira Vieira and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Traditional rotorcraft airfoil design is based on steady-state aerodynamics, despite the many sources of unsteady-flow in forward flight. At high-thrust and high-speed conditions, the rotor may be susceptible to dynamic stall; consequently, large margins are necessary to prevent fatigue loads on the blades and pitch links, limiting operation under high altitudes, payload, and temperatures, as well as during maneuvers.This work revises typical design requirements and proposes new ways to qualify airfoils in dynamic stall. A number of design studies are conducted to better understand the relation between airfoil shape and dynamic stall behavior. The design manipulations are handled by an inverse-design, conformal mapping method, and unsteady Reynolds-averaged Navier-Stokes equations are used to predict the unsteady aerodynamic performance. In unsteady flow, the occurrence of aerodynamic lags in the development of pressures, boundary-layer separation, and viscous-inviscid interactions suggest more strict requirements than in steady flow. In order to postpone the onset of dynamic stall, the design needs to handle competing leading- and trailing-edge separation mechanisms, which are heavily influenced by shock waves and laminar-turbulent transition effects. It is found that a particular tailoring of the trailing-edge separation development can provide adequate dynamic stall characteristics and minimize penalties in drag and nose-down pitching moments. At the same time, a proper design of the nose shape is required to avoid strong shock waves and prevent premature stall. A proof-of-concept airfoil is developed to improve dynamic stall behavior, while meeting other stringent requirements. Performance calculations using information obtained from comprehensive analysis (RCAS) based on a UH-60A helicopter suggest that an expansion of the operational envelope is possible, while also reducing hover drag, maintaining low pitching moments, and providing reasonable margins to drag rise at the maximum speed of the UH-60A helicopter.Finally, pitching wing calculations are conducted to demonstrate the proposed concepts in three-dimensional flow. The new wing experiences a more favorable dynamic stall inception and considerable decreases in the integrated peak pitching moments compared to traditional designs.
Book Synopsis Airfoil Design and Data by : Richard Eppler
Download or read book Airfoil Design and Data written by Richard Eppler and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 569 pages. Available in PDF, EPUB and Kindle. Book excerpt: This detailed book describes a procedure for the design and analysis of subsonic airfoils. Contains 116 new airfoils for a wide range of Reynolds numbers and application requirements, including the input data for the computer code.
Book Synopsis An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence by :
Download or read book An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence written by and published by . This book was released on 2003 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Transition and Turbulence Structure in the Boundary Layers of an Oscillating Airfoil by : J. DeRuyck
Download or read book Transition and Turbulence Structure in the Boundary Layers of an Oscillating Airfoil written by J. DeRuyck and published by . This book was released on 1989 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Objectives of this investigation were: 1) to identify the conditions under which a sinusoidally oscillating NACA 0012 airfoil operates with a leading edge separation bubble and the conditions under which it operates with leading edge stall; 2) to conduct complete boundary layer and near wake survey in the presence of the leading edge separation bubble; and 3) to investigate the flow near the trailing edge and in the near wake while the airfoil was undergoing leading edge stall. The airfoil oscillates about an axis at 25% chord from the leading edge, with a nominal reduced frequency of 0.3 and Reynolds number of 300,000. Experiments were made at 4 to 14, 5 to 15, 6 to 16 and 8 to 18 deg angle of attack. It was found that the most probable cause of leading edge stall was due to the leading edge separation bubble burst which occurred soon after static stall limit was exceeded. Leading edge stall is not due to the rapid upstream movement of the trailing edge separation. The velocity vectors and the Reynolds stress tensors were measured using a slanted rotating single sensor hot-wire. The complete suction side boundary layer profile and the near wake was surveyed at 5-15 deg oscillation where no interaction is observed between leading edge and trailing edge flows. Keywords: Unsteady aerodynamics; Dynamic stall; High angle of attack; Flow separation; Rotorcraft; Wake; Unsteady flow transition; Belgium. (EDC).
Book Synopsis Analysis of Low-Speed Unsteady Airfoil Flows by : Tuncer Cebeci
Download or read book Analysis of Low-Speed Unsteady Airfoil Flows written by Tuncer Cebeci and published by Springer. This book was released on 2009-09-02 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: The standard textbooks on aerodynamics usually omit any discussion of un steady aerodynamics or, at most, consider it only in a single chapter, based on two justifications. The first is that unsteady aerodynamics should be regarded as a specialized subject required "only" in connection with understanding and an alyzing aeroelastic phenomena such as flutter and gust response, and therefore should be dealt with in related specialist books. The second reason appears to be reluctance to discuss aerodynamics with the inclusion of the time-dependent terms in the conservation equations and the boundary conditions for fear that added complications may discourage the reader. We take the opposite view in this book and argue that a full understanding of the physics of lift generation is possible only by considering the unsteady aerody namics of the starting vortex generation process. Furthermore, certain "steady" flows are inherently unsteady in the presence of flow separation, as for example the unsteady flow caused by the Karman vortex shedding downstream of a cylin der and "static" airfoil stall which is an inherently unsteady flow phenomenon. Therefore, it stands to reason that a unified treatment of aerodynamics that yields steady-state aerodynamics as a special case offers advantages. This rea soning is strengthened by the developments in computational fluid dynamics over the past forty years, which showed that accurate steady-state solutions can be obtained efficiently by solving the unsteady flow equations.
Book Synopsis Summary of Low Speed Airfoil Data by : Michael S. Selig
Download or read book Summary of Low Speed Airfoil Data written by Michael S. Selig and published by Soartech. This book was released on 1995 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (France) Publisher : ISBN 13 : Total Pages :613 pages Book Rating :4.:/5 (227 download)
Book Synopsis Unsteady Aerodynamics by : ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (France)
Download or read book Unsteady Aerodynamics written by ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (France) and published by . This book was released on 1978 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Symposium identified the need for carefully conceived experimental unsteady flow data, particularly for both unseparated and separated two- and three-dimensional turbulent boundary layers. Detailed, accurate measurements of critical flow parameters was encouraged. It was agreed that linearized theories of unsteady inviscid flows provided a useful basis for many engineering applications, particularly in the early design stages of aircraft, but for more reliable calculations in the transonic and supersonic regimes the emphasis should be on development of non-linear numerical methods. Transonic numerical codes are increasingly efficient but their validity and accuracy needs assessment. Future calculations should include boundary layer effects even if no shock-wave interaction is included. The importance of Reynolds number on the dynamic stall was indicated. It was advised that serious consideration should be given to the development of a manual aeroelasticity of turbo-machines. An important factor in determining the characteristics of a rotor blade is the interaction of the blade with vortices shed by other blades. Research is required on the nature of this interaction and its effect on the dynamic stall of the blade. (Author).
Book Synopsis Analysis of Low-speed Unsteady Airfoil Flows by :
Download or read book Analysis of Low-speed Unsteady Airfoil Flows written by and published by Springer. This book was released on 2005 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an introduction to unsteady aerodynamics with emphasis on the analysis and computation of inviscid and viscous two-dimensional flows over airfoils at low speeds. It begins with a discussion of the physics of unsteady flows and an explanation of lift and thrust generation, airfoil flutter, gust response and dynamic stall. This is followed by an exposition of the four major calculation methods in currents use, namely inviscid-panel, boundary-layer, viscous-inviscid interaction and Navier-Stokes methods. Examples are provided to demonstrate the use of each method and panel and interactive boundary layer codes are included on the CD-ROM. Undergraduate and graduate students, teachers, scientists and engineers concerned with aeronautical, hydronautical and mechanical engineering problems will gain understanding of the physics of unsteady low-speed flows and an ability to analyze these flows with modern computational methods.
Book Synopsis Recent Development of Aerodynamic Design Methodologies by : Kozo Fujii
Download or read book Recent Development of Aerodynamic Design Methodologies written by Kozo Fujii and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics (CFD) has made remarkable progress in the last two decades and is becoming an important, if not inevitable, analytical tool for both fundamental and practical fluid dynamics research. The analysis of flow fields is important in the sense that it improves the researcher's understanding of the flow features. CFD analysis also indirectly helps the design of new aircraft and/or spacecraft. However, design methodologies are the real need for the development of aircraft or spacecraft. They directly contribute to the design process and can significantly shorten the design cycle. Although quite a few publications have been written on this subject, most of the methods proposed were not used in practice in the past due to an immature research level and restrictions due to the inadequate computing capabilities. With the progress of high-speed computers, the time has come for such methods to be used practically. There is strong evidence of a growing interest in the development and use of aerodynamic inverse design and optimization techniques. This is true, not only for aerospace industries, but also for any industries requiring fluid dynamic design. This clearly shows the matured engineering need for optimum aerodynamic shape design methodologies. Therefore, it seems timely to publish a book in which eminent researchers in this area can elaborate on their research efforts and discuss it in conjunction with other efforts.
Book Synopsis New Results in Numerical and Experimental Fluid Mechanics XII by : Andreas Dillmann
Download or read book New Results in Numerical and Experimental Fluid Mechanics XII written by Andreas Dillmann and published by Springer Nature. This book was released on 2019-09-26 with total page 867 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers contributions to the 21st biannual symposium of the German Aerospace Aerodynamics Association (STAB) and the German Society for Aeronautics and Astronautics (DGLR). The individual chapters reflect ongoing research conducted by the STAB members in the field of numerical and experimental fluid mechanics and aerodynamics, mainly for (but not limited to) aerospace applications, and cover both nationally and EC-funded projects. Special emphasis is given to collaborative research projects conducted by German scientists and engineers from universities, research-establishments and industries. By addressing a number of cutting-edge applications, together with the relevant physical and mathematics fundamentals, the book provides readers with a comprehensive overview of the current research work in the field. The book’s primary emphasis is on aerodynamic research in aeronautics and astronautics, and in ground transportation and energy as well.
Book Synopsis Special Course on Inverse Methods for Airfoil Design for Aeronautical and Turbomachinery Applications by :
Download or read book Special Course on Inverse Methods for Airfoil Design for Aeronautical and Turbomachinery Applications written by and published by . This book was released on 1990 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This lecture series is devoted to major aspects of aerofoil design both for aeronautical and turbomachine application. These include: (1) optimisation of target pressure and velocity distribution. Both direct optimisation resulting from an inverse boundary layer calculation and an iterative optimisation of the loses are presented. (2) aerofoil design by means of inverse methods. This ranges from simple parametric definitions of two- dimensional cross sections to a detailed numerical definition of three dimensional shapes. blade or airfoil designs are normally made in two steps, and the lectures are accordingly grouped into two parts. First, optimisation of target pressure and velocity distributions are discussed taking into account the required performance and the lost mechanisms in the boundary layer. Both direct optimisation resulting from an inverse boundary layer calculation, and an iterative optimisation by minimisation of the losses are presented. It is clear from both procedures that inclusion of off-design operation is one of the greatest difficulties involved in blade or airfoil operation. The second part gives an overview of the numerous inverse blade design methods that have been developed both for turbomachinery and aeronautical applications. This ranges from simple parameter definitions of two-dimensional cross-sections to the full three-dimensional definition of wings and blade channels."--DTIC.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Aerodynamic Design of an Advanced Rotor Airfoil by :
Download or read book The Aerodynamic Design of an Advanced Rotor Airfoil written by and published by . This book was released on 1978 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering written by and published by . This book was released on 1971 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)
Book Synopsis Effects of Specific Types of Surface Roughness on Boundary-layer Transition by : Laurence K. Loftin
Download or read book Effects of Specific Types of Surface Roughness on Boundary-layer Transition written by Laurence K. Loftin and published by . This book was released on 1946 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summary: Tests were conducted with two typical low-drag airfoils of 90-inch chord to determine the effects of surface projections, grooves, and sanding scratches on boundary-layer transition. The Reynolds number at which a spanwise row of cylindrical projections would cause premature transition was determined for a range of Reynolds number from approximately 3 x 106 to 10 x 106. Data were obtained for projections of various sizes and chordwise locations on both low-drag airfoils. The results were analyzed on the assumption that the critical airfoil Reynolds number for a given projection was a function only of the local-flow conditions around the projection. This assumption neglected possible effects of tunnel turbulence, pressure gradient, boundary-layer Reynolds number, and the original extent of the laminar flow. The data correlated on the basis of this assumption within a range of critical airfoil Reynolds number of ±0.5 x 106 and within a range of projection height of ±0.002 inch. The tests of surface grooves and sanding scratches indicated that, for the range of Reynolds number investigated, the laminar boundary layer was much less sensitive to surface grooves and sanding scratches than to projections above the surface.
Book Synopsis Calculation of Boundary Layers Near the Stagnation Point of an Oscillating Airfoil by : Tuncer Cebeci
Download or read book Calculation of Boundary Layers Near the Stagnation Point of an Oscillating Airfoil written by Tuncer Cebeci and published by . This book was released on 1983 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of an investigation of boundary layers close to the stagnation point of an oscillating airfoil are reported. Two procedures for generating initial conditions - the characteristics-box scheme and a quasi-static approach - were investigated, and the quasi-static approach was shown to be appropriate provided the initial region was far from any flow separation. With initial conditions generated in this way, the unsteady boundary-layer equations were solved for the flow in the leading-edge region of a NACA 0012 airfoil oscillating from 0 degrees to 5 degrees. Results were obtained for both laminar and turbulent flow, and, in the latter case, the effect of transition was assessed by specifying its occurrence at different locations. The results demonstrate the validity of the numerical scheme and suggest that the procedures should be applied to calculation of the entire flow around oscillating airfoils. (Author).
Book Synopsis Design and Analytical Study of a Rotor Airfoil by : L. U. Dadone
Download or read book Design and Analytical Study of a Rotor Airfoil written by L. U. Dadone and published by . This book was released on 1978 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
