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| Author | : Luiz M. Lourenco |
| Publisher | : |
| Total Pages | : 86 |
| Release | : 1993 |
| Genre | : Aerofoils |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 704 |
| Release | : 1995 |
| Genre | : Aeronautics |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 10 |
| Release | : 1988 |
| Genre | : |
| ISBN | : |
Experiments were conducted on a NACA-0015 airfoil undergoing low constant pitch rates to study the effects of dynamic stall formation on the airfoil upper surface pressure field. The airfoil was pitched about pivot locations of 0.25c, 05c, and 0.75c at nondimensional pitch rates below 0.2. Lift and drag coefficients were evaluated for all cases, and smoke flow visualization at low pitch rates was studied for the quarter chord pivot location. Results indicate that the greatest increases in lift due to the pitching motion occur prior to the nondimensional pitch rate of 0.1 for all three pivot locations. The effects of pitch rate on the maximum lift and drag values appear similar for the three pivot locations studied. Lift to drag ratios show significant enhancement even at very low nondimensional rates. Flow visualization indicates that the leading edge dynamic stall vortex is present even at very low nondimensional pitch areas. Keywords: Aerodynamic lift/drag; Pitch motion; Airfoils; Leading edges; Stall vortices; Aerodynamic forces; Unsteady flow; Reprints.
| Author | : Eugene E. Covert |
| Publisher | : |
| Total Pages | : 34 |
| Release | : 1986 |
| Genre | : |
| ISBN | : |
Unsteady excitation was generated by a rotating elliptical cylinder located below and behind the airfoil. This produced an unsteady flow of approximately constant phase. Four regions were identified within the unsteady turbulent boundary layer and the viscous sublayer was most affected by the unsteady flow. The velocity phase shift was found to be a function of the reduced frequency of the rotating elliptical cylinder. This phenomena was examined experimentally and analytically.
| Author | : A. Krothapalli |
| Publisher | : |
| Total Pages | : 26 |
| Release | : 1988 |
| Genre | : |
| ISBN | : |
A whole field experimental technique, commonly referred to as Particle Image Velocimetry, was used for the measurement of the instantaneous two-dimensional velocity fields about an impulsively started NACA 0012 airfoil at high angles of attack. The velocity field was measured with sufficient accuracy, such that the time evolution of the vorticity field was obtained. The experiments were performed in a towing at a Reynolds number of 1400, based on the chord of the airfoil. For angles of attack greater than about 20 deg, the flow field at the upper surface of the airfoil show large scale vortical motions with the following time dependent scenario. At the initial stages of the airfoil startup, a separation bubble at the leading edge was generated and with time, it grows into an isolated primary vortex which dominated the whole flow field. Trailing behind this primary vortex were two counter rotating vortices. This multiple vortex structure grow together and move along the upper surface until it reaches the trailing edge. At this time, the primary vortex induces a trailing edge vortex. The primary and trailing edge vortices then form the wake flow field.
| Author | : |
| Publisher | : |
| Total Pages | : 684 |
| Release | : 1989 |
| Genre | : Aerodynamics, Transonic |
| ISBN | : |
| Author | : Pushkar Ghosh Choudhuri |
| Publisher | : |
| Total Pages | : 208 |
| Release | : 1995 |
| Genre | : |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 156 |
| Release | : 1971 |
| Genre | : |
| ISBN | : |
| Author | : Anjaneyulu Krothapalli |
| Publisher | : |
| Total Pages | : 132 |
| Release | : 1989 |
| Genre | : |
| ISBN | : |
An experimental and numerical simulations have been carried out to study the unsteady flow past an impulsively started NACA 0012 airfoil at different angles of attack (O
| Author | : T. Cebeci |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 487 |
| Release | : 2012-12-06 |
| Genre | : Technology & Engineering |
| ISBN | : 1461249260 |
The Third Symposium on Numerical and Physical Aspects of Aerodynamic Flows, like its immediate predecessor, was organized with emphasis on the calculation of flows relevant to aircraft, ships, and missiles. Fifty-five papers and 20 brief communications were presented at the Symposium, which was held at the California State University at Long Beach from 21 to 24 January 1985. A panel discussion was chaired by A. M. O. Smith and includeq state ments by T. T. Huang, C. E. lobe, l. Nielsen, and C. K. Forester on priorities for future research. The first lecture in memory of Professor Keith Stewartson was delivered by J. T. Stuart and is reproduced in this volume together with a selection of the papers presented at the Symposium. In Volume II of this series, papers were selected so as to provide a clear indication of the range of procedures available to represent two-dimensional flows, their physical foundation, and their predictive ability. In this volume, the emphasis is on three-dimensional flows with a section of five papers concerned with unsteady flows and a section of seven papers on three dimensional flows: The papers deal mainly with calculation methods and encompass subsonic and transonic, attached and separated flows. The selec tion has been made so as to fulfill the same purpose for three-dimensional flows as did Volume II for two-dimensional flows.
