دانلود رایگان مقاله لاتین تشکیل گردابه از سایت الزویر
عنوان فارسی مقاله:
تشکیل گردابه در جناح برآمدگی و اثرات آنها بر درگ
عنوان انگلیسی مقاله:
Formation of vortices on a tubercled wing, and their effects on drag
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Humpback whales are enormous creatures, yet they remain remarkably agile. They can execute underwater somersaults and swim at high angles of attack during feeding [1], feats unique among Baleen whales. Their pectoral flippers are also unique, featuring bumps on the leading edges, termed tubercles, and it is now known that these tubercles are, in part, responsible for the Humpback whale’s nimbleness [2]. Tubercles can be categorised by two main parameters, the amplitude, which refers to the distance between a tubercle peak and neighbouring trough, and the wavelength, which refers to the distance between two neighbouring tubercle troughs or peaks. Research has revealed that tubercles create pairs of counter-rotating, streamwise vortices [3–5] as shown in Fig. 1. It was proposed by Hansen et al. [6] that the strength of these vortices is directly related to the Amplitude-to-Wavelength ratio, where increasing this ratio would result in a greater local sweep of the leading edge and an increase in the vortices’ strengths. To the authors’ knowledge there have been no investigations into the effect of wing sweep on the relative strengths of the pairs of streamwise, counter-rotating vortices. The main effects of tubercles are a softening and delaying of stall [2,7–9], however, they can also provide significant reductions in drag, as well as increases in the lift-to-drag ratio, for a swept wing at pre-stall angles of attack [10,11]. The aim of the present study is to further investigate the effects of tubercles on swept wing drag, and to determine how tubercles are able to reduce drag. * Corresponding author. E-mail address: michael.bolzon@adelaide.edu.au (M.D.P. Bolzon). Fig. 1. Diagram of a wing with leading edge tubercles and the approximate location and sign of the vortices produced. CCW refers to a counter-clockwise rotation and CW refers to a clockwise rotation. To investigate the counter-rotating, streamwise vortex pairs produced by the tubercles, a wake survey has been conducted on the same two wings used in Bolzon et al. [10]. From this wake survey the vorticity distributions and the profile and induced drag coeffi- cients of these wings have been calculated and compared.
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کلمات کلیدی:
The formation mechanism and impact of streamwise vortices on NACA ... aip.scitation.org/doi/pdf/10.1063/1.4896748 by N Rostamzadeh - 2014 - Cited by 23 - Related articles of streamwise vortices whose development is accompanied by flow separation in ... tubercle-modified lifting bodies, the formation mechanism of streamwise ... Force Measurements and Wake Surveys of a Swept Tubercled Wing ... ascelibrary.org/doi/full/10.1061/%28ASCE%29AS.1943-5525.0000683 One wing had a smooth leading edge, while the other wing had a tubercled ... drag coefficient over the peaks where the tubercle vortices produced downwash. ...... 2015) and that tubercles can modulate an LSB formation (Rostamzadeh et al. The formation mechanism and impact of streamwise vortices on NACA ... adsabs.harvard.edu/abs/2014PhFl...26j7101R by N Rostamzadeh - 2014 - Cited by 23 - Related articles The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil's ... While the aerodynamic benefits of full-span tubercled wings have been ... Biologically Inspired Wing Leading Edge for Enhanced Wind Turbine ... https://arc.aiaa.org/doi/pdf/10.2514/6.2011-3533 by K Isaac - Cited by 10 - Related articles Jun 30, 2011 - suggested in previous studies can probably be attributed to the formation of a complex vortex structure on the tubercled wings. A local trailing ... Vortex lift - Wikipedia https://en.wikipedia.org/wiki/Vortex_lift Vortex lift is a form of lift generated by delta wings operating at high angles of attack. How it works[edit]. Vortex lift works by capturing vortices generated from the sharply swept leading edge of the wing. The vortex, formed roughly parallel to the leading edge of the wing, ... Sustainable Development: Proceedings of the 2015 International ... https://books.google.com/books?isbn=9814749923 Liandong Zhu, Ahmed Ouadha - 2016 - Science The streamwise vortices originated by the tubercles enhanced the flow ... them to move towards the valleys causing a coalescence of fluid between tubercle peaks. ... to low pressure resulted in spanwise flow and the formation of tip vortices.
