Download or read book Airfoil Boundary layer Transition Due to Large Isolated 3 D Roughness Elements in a Favorable Pressure Gradient written by Matthew Joseph Cummings and published by . This book was released on 1995 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 4th AIAA Theoretical Fluid Mechanics Meeting 05 5053 05 5386 written by and published by . This book was released on 2005 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 1996 with total page 1422 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Review of the Effect of Distributed Surface Roughness on Boundary layer Transition written by A. L. Braslow and published by . This book was released on 1960 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: A discussion is presented on the transition phenomena associated with distributed roughness, a correlation of three-dimensional roughness effects at both subsonic and supersonic speeds, and the effect of laminar boundary-layer stability as influenced by heat transfer, pressure gradients, and boundary-layer control on the sensitivity of laminar flow to distributed roughness. Results indicate that the transition-triggering mechanism of three-dimensionaltype surface roughness appears to be the same at supersonic and subsonic speeds. In either case, a Reynolds number based on the height of the roughness and the local flow conditions at the top of the roughness can be used to predict with reasonable accuracy the height of threedimensional roughness required to cause premature transition. Neither the three-dimensional roughness Reynolds number nor the lateral spread of turbulence behind the roughness is changed to any important extent by increasing the laminar boundary-layer stability to theoretically small disturbances. Therefore, for a given stream Mach number and Reynolds number, surface cooling, boundary-layer suction, or a favorable pressure gradient will, in the presence of three-dimensional roughness, promote rather than delay transition. (Author).

Download or read book 34th Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 1996 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Review of Factors Affecting Boundary layer Transition written by Albert L. Braslow and published by . This book was released on 1966 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interaction of a Three Dimensional Roughness Element with a Laminar Boundary Layer written by P. S. Klebanoff and published by . This book was released on 1987 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation is described that is directed toward extending the technical database and furthering our understanding of boundary layer transition induced by three-dimensional roughness elements. The investigation was carried out in an unsteady wind tunnel, principally with hemispherical roughness elements, in a well characterized zero-pressure gradient laminar boundary layer on a flat plate. Attention was directed toward the following aspects of the behavior of a three dimensional roughness element: (1) the critical Reynolds number of transition and the effect of aspect ratio thereon, (2) eddy generation is steady and unsteady flows, (3) is the fundamental process stability governed, and (4) the evolutionary change in mean velocity and intensity of the velocity fluctuation associated with the transition to fully developed turbulent flow.

Download or read book Influence of Surface Static pressure Orifices on Boundary layer Transition written by Dan M. Somers and published by . This book was released on 1982 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1993 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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:

Download or read book Turbulent Boundary Layers written by Helmut E. Weber and published by . This book was released on 1979 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 41st AIAA Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 2003 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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:

Download or read book Effect of Surface Waviness on Transition in Three Dimensional Boundary Layer Flow written by and published by . This book was released on 1996 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Large Distributed Roughness Near an Airfoil Leading Edge on Boundary layer Development and Transition written by Michael Fort Kerho and published by . This book was released on 1995 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of the effects of large distributed roughness located near the leading-edge of an airfoil has been performed to determine the effect on boundary-layer development and transition. Boundary-layer measurements were carried out on a two-dimensional NACA 0012 airfoil with a 21" chord. The distributed roughness used was in the form of densely packed large hemispherical elements applied to the leading-edge region of the airfoil section. The size of the distributed roughness was greater than or on the order of the laminar boundary-layer thickness. The roughness used is of the type and density observed to occur during the initial glaze ice accretion process. Detailed boundary-layer measurements were obtained through the use of hot-wire anemometry at Reynolds numbers of 0.75 $times$ 10$sp6$, 1.25 $times$ 10$sp6$, and 2.25 $times$ 10$sp6$. These measurements included mean and fluctuating velocity, turbulence intensity, flowfield intermittency, frequency content, and associated integral parameters. Both the clean model and roughness induced transitional boundary-layers were studied in great detail. Results from this investigation have shown that the transitional boundary-layer induced by large distributed roughness is markedly different from the clean model Tollmein-Schlicting induced transition process. For the type of roughness used in this study no fully developed turbulent boundary-layers were observed to occur at the roughness location, even though roughness heights were substantially greater than empirically determined critical roughness heights required to cause transition. Instead, the large distributed roughness was observed to trigger a transitional boundary-layer at or very near the roughness location. This transitional boundary-layer required a substantial chordwise extent to obtain a fully developed turbulent state. Turbulence intensity levels in the roughness induced transitional region were observed to be relatively low as compared to the clean model transitional region. In general, the clean model transitional process was substantially more energetic than that observed for the roughness induced boundary-layer. A new method for determining the location and extent of the transitional region by integrating the profiles of intermittency is also presented.