Download or read book Effect of Roughness on Properties of Airfoils written by O. Schrenk and published by . This book was released on 1926 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first group of a large series of contemplated experiments on the effect of roughness was intended to show the effect of great roughness on airfoils of various sizes and attitudes.

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 The Effects of Roughness at High Reynolds Numbers on the Lift and Drag Characteristics of Three Thick Airfoils written by Frank T. Abbott and published by . This book was released on 1944 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: In connection with studies of airfoils applicable to large high-speed aircraft, the effects of roughness on three 22-percent-thick airfoils were investigated. The tests were made over a range of Reynolds numbers from about 6,000,000 to 26,000,000 for the airfoils smooth and with roughness strips applied to the surfaces. The results indicated that for the roughened models the scale effect was generally favorable.

Download or read book Effect of Roughness on Airfoils written by O. Schrenk and published by . This book was released on 1927 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Roughness on Advanced Airfoils written by Bombardier Aerospace and published by . This book was released on 1998 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents results of the second and third phases of a research program that studied the effects of roughness contamination on modern airfoils and wings. Phase two involved testing a Bombardier Aerospace proprietary supercritical airfoil section in a wind tunnel, and phase three involved a low-speed test of the Canadair Regional Jet wing in a larger wind tunnel. The performance of the tested models with different flap deflections, sweep angles, and roughness parameters was compared to computational fluid dynamics (CFD) results. A quasi-three-dimensional CFD model based on a viscous-inviscid coupling technique, using a panel method for the inviscid flow field and a two-dimensional compressible boundary layer with sweep and roughness effects, was calibrated using the results. Experimental results were also compared with Regional Jet flight test data. The results reveal the possibility of predicting the effects of roughness on aerodynamic performance.

Download or read book The Aerodynamic Characteristics of Airfoils as Affected by Surface Roughness written by Ray W. Hooker and published by . This book was released on 1933 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect on airfoil characteristics of surface roughness of varying degrees and types at different locations on an airfoil was investigated (at high values of the Reynolds number in the N.A.C.A. variable-density wind tunnel).

Download or read book Investigation of Effects of Surface Roughness on Symmetric Airfoil Lift and Lift to drag Ratio written by Mark Thomas Beierle and published by . This book was released on 1998 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research investigated the effects of surface roughness in the form of protuberances on the lift and lift-to-drag ratio of an airfoil with a NACA 0015 profile. Russian researchers first recorded the positive effect on lift from naturally formed surface protuberances in 1984 and reported on their research in 1991. Based on experimental studies, the Russian researchers identified a protuberance geometry on a low aspect ratio wing which created both additional lift and an improved lift-to-drag ratio for a given angle-of-attack over the low to moderate angle-of-attack region. The primary objective of this research was to develop a phenomenological understanding of the flow physics related to the effects of surface roughness on the lift and lift-to-drag ratio of a symmetric airfoil. Two wind tunnel experiments were conducted at the University of Maryland's Glenn L. Martin Wind Tunnel to investigate the effect of protuberance coverage, size, and density. A two-dimensional computational experiment studied the effect of protuberance location, geometry, and spacing using the OVERFLOW Navier-Stokes flow solver. Results indicated that the variation of the aerodynamic lift and the lift-to-drag ratio for symmetric airfoils and wings populated with protuberances is due to the increased pressure induced by a recirculation region downstream of the protuberance. An alternative understanding based on changes in the effective camber and thickness of the airfoil was developed. Wind tunnel and computational results qualitatively validated the lift enhancement on symmetric airfoils due to surface roughness. Results indicated that the magnitude of the lift increment was strongly dependent on airfoil angle-of-attack and protuberance height and had a weak dependence on protuberance width and spacing. Just one configuration, based on a wind tunnel test of a wing with protuberances, generated a larger lift-to-drag ratio compared to a smooth wi

Download or read book Environmentally Induced Surface Roughness Effects on Laminar Flow Airfoils written by M.B. Bragg and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Roughness on Airfoils written by Oskar Schrenk and published by . This book was released on 1927 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: We will here report on the effects of coarsely roughening not only the pressure side but also the suction or upper side of airfoils, as the first group of a larger series of experiments.

Download or read book The Effect of Roughness Applied on an Airfoil at Or Near the Leading Edge at Low Reynolds Numbers written by Diane Ruth Bloch and published by . This book was released on 1986 with total page 546 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.

Download or read book Effects of Grit Roughness and Pitch Oscillations on the S809 Airfoil written by R. Reuss Ramsay and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effects of Roughness on an Airfoil at Low Reynolds Numbers written by Arthur F. Huber and published by . This book was released on 1985 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Airfoil Thickness and Maximum Lift Coefficient on Roughness Sensitivity written by and published by . This book was released on 2005 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: A matrix of airfoils has been developed to determine the effects of airfoil thickness and the maximum lift to leading-edge roughness. The matrix consists of three natural-laminar-flow airfoils, the S901, S902, and S903, for wind turbine applications. The airfoils have been designed and analyzed theoretically and verified experimentally in the Pennsylvania State University low-speed, low-turbulence wind tunnel. The effect of roughness on the maximum life increases with increasing airfoil thickness and decreases slightly with increasing maximum lift. Comparisons of the theoretical and experimental results generally show good agreement.

Download or read book Unsteady Aerodynamics Aeroacoustics and Aeroelasticity of Turbomachines written by Kenneth C. Hall and published by Springer Science & Business Media. This book was released on 2006-05-11 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is a collection of technical papers that were presented at the 10th International Symposium on Unsteady Aerodynamics, Aeroacoustics, and Aeroelasticity of Turbomachines held September 8-11, 2003 at Duke University in Durham, North Carolina. The papers represent the latest in state of the art research in the areas of aeroacoustics, aerothermodynamics, computational methods, experimental testing related to flow instabilities, flutter, forced response, multistage, and rotor-stator effects for turbomachinery.

Download or read book Effects of Roughness on Advanced Airfoils and Wings written by Faith Tezok and published by . This book was released on 1995 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aerodynamic Performance of Transonic and Subsonic Airfoils written by Qiang Zhang and published by . This book was released on 2005 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: