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Book Investigation of Effects of Surface Roughness on Symmetric Airfoil Lift and Lift to drag Ratio

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

Book Effects of Specific Types of Surface Roughness on Boundary layer Transition

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 The Effects of Roughness at High Reynolds Numbers on the Lift and Drag Characteristics of Three Thick Airfoils

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.

Book EBOOK Fundamentals of Aerodynamics SI units

Download or read book EBOOK Fundamentals of Aerodynamics SI units written by John Anderson and published by McGraw Hill. This book was released on 2011-06-16 with total page 1113 pages. Available in PDF, EPUB and Kindle. Book excerpt: In keeping with its bestselling previous editions, Fundamentals of Aerodynamics, Fifth Edition by John Anderson, offers the most readable, interesting, and up-to-date overview of aerodynamics to be found in any text. The classic organization of the text has been preserved, as is its successful pedagogical features: chapter roadmaps, preview boxes, design boxes and summary section. Although fundamentals do not usually change over time, applications do and so various detailed content is modernized, and existing figures are replaced with modern data and illustrations. Historical topics, carefully developed examples, numerous illustrations, and a wide selection of chapter problems are found throughout the text to motivate and challenge students of aerodynamics.

Book Drag Due to Two dimensional Surface Roughness in a Turbulent Boundary Layer Mach 3 with and Without Heat Transfer

Download or read book Drag Due to Two dimensional Surface Roughness in a Turbulent Boundary Layer Mach 3 with and Without Heat Transfer written by William J. Monta and published by . This book was released on 1968 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Dissertation Abstracts International

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1999 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1985 with total page 1346 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Effect of Roughness on Properties of Airfoils

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.

Book Summary of Low Speed Airfoil Data

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:

Book The Aerodynamic Characteristics of Airfoils as Affected by Surface Roughness

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).

Book NACA Wartime Reports Series L

Download or read book NACA Wartime Reports Series L written by John A. Zalovcik and published by . This book was released on 1944 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: A flight investigation was made on a wing section of a P-47D airplane to determine the effect of roughness on wing profile drag with transition fixed far forward. Surveys of the wake were made for two surface conditions with transition fixed by a thread at 5 percent chord back of the leading edge on the upper and lower surfaces. One of the surveys was made with the surfaces smooth; the other survey was made with the surfaces roughed by an application of camouflage paint behind the thread. The surface roughness produced by the camouflage paint was made up of particles of about 0.0012 inch in height and numbering roughly 40,000 per square inch.

Book Investigation of the Effect of Airfoil Roughness for Stall Control

Download or read book Investigation of the Effect of Airfoil Roughness for Stall Control written by Harith Vadari and published by . This book was released on 2001 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: