Transition and Turbulence Structure in the Boundary Layers of an Oscillating Airfoil PDF Download
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Author: J. DeRuyck Publisher: ISBN: Category : Languages : en Pages : 102
Book Description
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).
Author: J. DeRuyck Publisher: ISBN: Category : Languages : en Pages : 102
Book Description
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).
Author: J. de Ruyck Publisher: ISBN: Category : Languages : en Pages : 91
Book Description
The main objective of this work is to provide experimental information about velocity fields and turbulence structures in unsteady flows. A NACA 0012 airfoil oscillates around an axis at 25% chord distance from the leading edge, with a sinusoidal motion. Instantaneous distributions of velocity as well as all non-zero Reynolds stresses are determined in the profile boundary layers. Measurements are performed at various incidences, from non-stalled to deep stalled flow conditions. The reduced frequency is 0.3 at a chord Reynolds number of 300,000. A slanted rotating hot wire is used and the angular calibration characteristics of the wire are applied in order to detect and measure reversed flows. Instantaneous detailed flow and turbulence patterns of the periodic separation vortex are presented and discussed. These patterns are obtained from traverses at 8 chordwise positions along the suction side of the blade. Keywords include: Data reduction, Computer applications, Oscillating airfoil, Dynamic stall, Experimental velocity fields, and Reynolds stresses.
Author: J. De Ruyck Publisher: ISBN: Category : Languages : en Pages : 89
Book Description
The main objective of the present study is to provide experimental information about turbulence structures in unsteady flow fields. Measurements were made in the wake of a NACA 0012 airfoil oscillating in pitch around an axis at 25% chord distance from the leading edge with a sinusoidal motion. Instantaneous profiles of velocity and all non-zero Reynolds stresses are determined at 48 phase angles within the oscillation period. Measurements were made at .7, 2, 5, 10 and 20% chord downstream of the trailing edge. Various incidences, from zero to just above stall limit, various amplitudes and frequencies were considered.
Author: Publisher: ISBN: Category : Aeronautics Languages : en Pages : 380
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: Andreas Dillmann Publisher: Springer ISBN: 3319645196 Category : Technology & Engineering Languages : en Pages : 735
Book Description
This book gathers contributions to the 20th 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. Though the book’s primary emphasis is on the aerospace context, it also addresses further important applications, e.g. in ground transportation and energy.
Author: Jorge Colman Lerner Publisher: BoD – Books on Demand ISBN: 9533076232 Category : Science Languages : en Pages : 728
Book Description
The book "Wind Tunnels and Experimental Fluid Dynamics Research" is comprised of 33 chapters divided in five sections. The first 12 chapters discuss wind tunnel facilities and experiments in incompressible flow, while the next seven chapters deal with building dynamics, flow control and fluid mechanics. Third section of the book is dedicated to chapters discussing aerodynamic field measurements and real full scale analysis (chapters 20-22). Chapters in the last two sections deal with turbulent structure analysis (chapters 23-25) and wind tunnels in compressible flow (chapters 26-33). Contributions from a large number of international experts make this publication a highly valuable resource in wind tunnels and fluid dynamics field of research.
Author: Lawrence W. Carr Publisher: ISBN: Category : Turbulence Languages : en Pages : 62
Book Description
A comprehensive literature search was conducted and those experiments related to unsteady turbulent boundary-layer behavior were cataloged. In addition, an international survey of industrial, university, and government research laboratories was made, in which new and ongoing experimental programs associated with unsteady turbulent boundary-layer research were identified. Pertinent references were reviewed and classified based on the technical emphasis of the various experiments that include instantaneous or ensemble-averaged profiles of boundary-layer variables are stressed. Detailed reviews that include descriptions of the experimental apparatus, flow conditions, summaries of acquired data, and significant conclusions are made. The measurements made in these experiments that exist in digital form have been stored on magnetic tape, and instructions are presented for accessing these data sets for further analysis. (Author).
Author: United States. Army Research Office Publisher: ISBN: Category : Military research Languages : en Pages : 284
Book Description
Vols. for 1977- consist of two parts: Chemistry, biological sciences, engineering sciences, metallurgy and materials science (issued in the spring); and Physics, electronics, mathematics, geosciences (issued in the fall).
Author: J. DeRuyck
Author: J. DeRuyck
Author: J. de Ruyck
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Author: J. De Ruyck
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Author: Andreas Dillmann
Author: Jorge Colman Lerner
Author: Lawrence W. Carr
Author: United States. Army Research Office