van Hinsberg, Nils (2021) Mean and unsteady loading on square prisms with rounded edges: Hard marine growth, incidence, and Reynolds number effects. Marine Structures (75). Elsevier. doi: 10.1016/j.marstruc.2020.102886. ISSN 0951-8339.
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Official URL: https://www.sciencedirect.com/science/article/pii/S0951833920301799
Abstract
A set of wind tunnel experiments was performed to study the average and fluctuating wind loading on an "infinite" 2D square prism with rounded edges of r/d = 0.16 for different heights of simulated hard marine growth at sub-to transcritical Reynolds numbers. It has already been shown, that a change in surface roughness from ks/d = 4.5x10-6 (smooth) to 1x10-3 (rough) on a similar prism at Alpha = 0deg and 45deg had large effects on the widths and the Reynolds numbers marking the boundaries of the various flow states. At Alpha = 45deg it furthermore led to a large Reynolds-number independency of the lift and drag forces and of the Strouhal number. For the present wind tunnel tests two additional values of ks/D were selected to obtain smaller increments in surface roughness: 4.5x10-4 (slightly rough) and 1.4x10-3 (very rough). Mean and fluctuating lift and drag forces, the main vortex shedding frequency, distributions of the mean surface pressures in the mid-span cross-section of the prism and the mean wake profiles were recorded simultaneously. The same two static angles of incidence, Alpha = 0deg and 45deg, were investigated for ReD = 60,000 to 12 million. For the prisms with smooth up to rough surfaces strong effects on the behaviour of all aerodynamic parameters with Reynolds number were found, whereas a further increase in ks/D induced hardly any additional effects. The absolute values of the aerodynamic parameters were found to be independent of a change in ks/D for the sub-to supercritical flow states. For the smooth and slightly rough prisms at Alpha = 0deg the supercritical flow state was present up to ReD = 12 million, whereas for the rougher prisms the upper transition and the transcritical flow states appeared at high Reynolds numbers. A change to alpha = 45deg induced little variation with ks/D for all aerodynamic coefficients. The overall behaviour of the force coefficients and the Strouhal number with ks/D and ReD were caused by motions of the transition, separation and reattachment locations.
Item URL in elib: | https://elib.dlr.de/137481/ | ||||||||
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Document Type: | Article | ||||||||
Title: | Mean and unsteady loading on square prisms with rounded edges: Hard marine growth, incidence, and Reynolds number effects | ||||||||
Authors: |
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Date: | January 2021 | ||||||||
Journal or Publication Title: | Marine Structures | ||||||||
Refereed publication: | Yes | ||||||||
Open Access: | Yes | ||||||||
Gold Open Access: | No | ||||||||
In SCOPUS: | Yes | ||||||||
In ISI Web of Science: | Yes | ||||||||
DOI: | 10.1016/j.marstruc.2020.102886 | ||||||||
Publisher: | Elsevier | ||||||||
ISSN: | 0951-8339 | ||||||||
Status: | Published | ||||||||
Keywords: | bluff body; edge roundness; Reynolds number; flow separation; marine growth; aerodynamics; surface roughness; square prism | ||||||||
HGF - Research field: | Aeronautics, Space and Transport | ||||||||
HGF - Program: | Aeronautics | ||||||||
HGF - Program Themes: | fixed-wing aircraft | ||||||||
DLR - Research area: | Aeronautics | ||||||||
DLR - Program: | L AR - Aircraft Research | ||||||||
DLR - Research theme (Project): | L - Flight Physics (old) | ||||||||
Location: | Göttingen | ||||||||
Institutes and Institutions: | Institute of Aeroelasticity > Aeroelastic Experiments | ||||||||
Deposited By: | van Hinsberg, Dr. Ir. Nils | ||||||||
Deposited On: | 24 Nov 2020 18:39 | ||||||||
Last Modified: | 02 May 2023 09:44 |
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