Current Search: Wind tunnels (x)
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Title
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Utilizing "bills" for drag reduction below transition on spherical bodies.
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Creator
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Adamson, James Edward., Florida Atlantic University, Tennant, Jeffrey S.
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Abstract/Description
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Russian experimenters Kozlov and Leonenko have reported substantial drag reduction on a sphere using a "bill" or "spike" extending from the body upstream into the flow. A systematic series of experiments was conducted to determine the extent of the reduction and to identify the parameters of the reported drag reduction effect. The tests were performed in the Florida Atlantic University Ocean Engineering Department's Aerolab wind tunnel. A sphere was fitted with tapering bills of various...
Show moreRussian experimenters Kozlov and Leonenko have reported substantial drag reduction on a sphere using a "bill" or "spike" extending from the body upstream into the flow. A systematic series of experiments was conducted to determine the extent of the reduction and to identify the parameters of the reported drag reduction effect. The tests were performed in the Florida Atlantic University Ocean Engineering Department's Aerolab wind tunnel. A sphere was fitted with tapering bills of various lengths, base diameters, and bill/sphere fillet radii. Experiments indicated that the effect was restricted to Reynolds numbers below 4.0 x 10^5 and that the drag of the sphere/spike combination was actually increased at Reynolds numbers greater than this. A smoke generator was used to visualize the drag reduction mechanism, which appears to be a recirculating cell at the base of the sphere/spike intersection.
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Date Issued
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1989
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PURL
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http://purl.flvc.org/fcla/dt/14514
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Subject Headings
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Drag (Aerodynamics), Wind tunnel models
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Format
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Document (PDF)
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Title
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Non-Invasive Measurement Methods for Transient Flows in Wind Tunnels.
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Creator
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Marcheggiani, Joseph P., Glegg, Stewart, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
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Abstract/Description
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A non-invasive transient state measurement method for wind tunnels would be very valuable as an experimental tool. Traditional measurement techniques for transient flows, e.g., hot wire anemometry, require sensors that are placed in the flow. Alternatively, particle image velocimetry (PIV) may be used to measure transient flows non intrusively, but applying PIV requires sensors that are expensive, and it may take months to process the data. The non-invasive measurement techniques considered...
Show moreA non-invasive transient state measurement method for wind tunnels would be very valuable as an experimental tool. Traditional measurement techniques for transient flows, e.g., hot wire anemometry, require sensors that are placed in the flow. Alternatively, particle image velocimetry (PIV) may be used to measure transient flows non intrusively, but applying PIV requires sensors that are expensive, and it may take months to process the data. The non-invasive measurement techniques considered in this thesis utilize sensors that are imbedded into the wall of a wind tunnel, or the response of a Kevlar walled wind tunnel to obtain the pressure time histories of a transient flow. These measurements are suitable and accurate for analyzing steady state flows but the feasibility of using them on time varying flows has yet to be explored. If this method proves possible, it would be very beneficial even if it is less accurate than current invasive methods because it would give results in real time. This thesis investigates a simple transient flow of the startup vortex of an airfoil caused by a step change in angle of attack. Based on thin airfoil theory, two models of an airfoil were created. It was determined that the response of a Kevlar wall can measure the unsteady lift of an airfoil.
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Date Issued
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2021
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PURL
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http://purl.flvc.org/fau/fd/FA00013837
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Subject Headings
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Wind tunnels, Transient flow (Aerodynamics), Measurement, Sensors
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Format
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Document (PDF)
