| Autor: |
Nicholas F. Jones, David M. Rooney, John C. Vaccaro |
| Rok vydání: |
2017 |
| Předmět: |
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| Zdroj: |
Volume 1B, Symposia: Fluid Measurement and Instrumentation; Fluid Dynamics of Wind Energy; Renewable and Sustainable Energy Conversion; Energy and Process Engineering; Microfluidics and Nanofluidics; Development and Applications in Computational Fluid Dynamics; DNS/LES and Hybrid RANS/LES Methods. |
| DOI: |
10.1115/fedsm2017-69399 |
| Popis: |
An experimental study was undertaken to investigate the influence of leading edge geometry and of relative curvature on the formation of a boundary layer on the surface of a cylinder aligned axially in a uniform flow. Hot wire anemometry was used to measure mean and fluctuating velocity components at a number of axial locations from the leading edge of cylinders of three different relative curvatures and two different leading edge shapes. In all cases a minimum relative axial length of greater than ten radii was examined, hence allowing adequate inspection of the formation region. Six cylinders were employed in the study, three with a blunt leading edge, and three with an ellipsoid of 3:1 ratio leading to the constant radius length. The Reynolds number based on cylinder radius (Rea = Uoa/v) varied from 3000 ≤ Rea ≤ 9000. The elliptical leading edge cylinders experienced laminar boundary layers, and the blunt cylinders created a separated bubble region followed by the development of a turbulent boundary layer. The laminar boundary layer was smaller than what a flat plate would produce at a corresponding length, and its experimental data generated profiles could be universalized with previously developed similarity variables. The turbulent boundary layer assumed a nearly constant velocity profile in the region 10 ≤ x/a ≤ 40, and its height grew proportionally to x1/3 rather than to x4/5 as for a flat plate. Streamwise turbulence intensities diminished rapidly with vertical distance from the surface of the cylinder, and also assumed a constant profile as relative axial distance increased. Over the limited range examined, changes in curvature were of secondary importance on relative boundary layer growth. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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