Aerodynamics of Low Reynolds Number Flyers by Wei Shyy, Yongsheng Lian, Jian Tang, Dragos Viieru, Hao Liu

By Wei Shyy, Yongsheng Lian, Jian Tang, Dragos Viieru, Hao Liu

Low Reynolds quantity aerodynamics is necessary to a couple of normal and man-made flyers. Birds, bats, and bugs were of curiosity to biologists for years, and lively research within the aerospace engineering group, encouraged via curiosity in micro air automobiles (MAVs), has been expanding swiftly. the first concentration of this publication is the aerodynamics linked to mounted and flapping wings. The booklet contemplate either organic flyers and MAVs, together with a precis of the scaling laws-which relate the aerodynamics and flight features to a flyer's sizing at the foundation of straightforward geometric and dynamics analyses, structural flexibility, laminar-turbulent transition, airfoil shapes, and unsteady flapping wing aerodynamics. The interaction among flapping kinematics and key dimensionless parameters similar to the Reynolds quantity, Strouhal quantity, and decreased frequency is highlighted. many of the unsteady carry enhancement mechanisms also are addressed, together with modern vortex, fast pitch-up and rotational stream, wake seize, and clap-and-fling.

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Extra resources for Aerodynamics of Low Reynolds Number Flyers

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This may not be appropriate, because a change in, for instance, body mass does not necessarily affect I. Therefore, if we intend to predict these effects on the wing-beat frequency, it is more suitable to include I as an independent parameter (Pennycuick, 1996): f = (mg)1/2 b−17/24 S−1/3 I −1/8 ␳ 3/8 . 22) Another relation observed by Pennycuick et al. (1996) is the effect of air speed on wing-beat frequency when body mass changes. 23) where k2 , k3 and k4 are proportional constants. 1 Upper and Lower Limits Can scaling arguments provide any information about limits on the size of flapping flyers capable of sustained flight?

5 illustrates that, at a fixed Reynolds number of 60,100, for the Eppler E374, a zigzag pattern appears in the lift–drag polar: 1. 75◦ , there is a long bubble on the airfoil surface, which leads to a large drag. 2. 82◦ ), the adverse pressure gradient on the upper surface grows, which intensifies the Tollmien–Schlichting (TS) wave, resulting in an expedited laminar–turbulent transition process. A shorter LSB leads to more airfoil surface covered by the attached turbulent boundary-layer flow, resulting in a lower drag.

For example, Roberts (1980), Davis et al. (1987), and Volino and Bohl (2004) developed models based on local turbulence levels; Mayle (1991), Praisner and Clark (2004), and Roberts and Yaras (2005) tested concepts by using the local Reynolds number based on the momentum thickness. These models use only one or two local parameters to predict the transition points and hence often oversimplify the downstream factors such as pressure gradient, surface geometry, and surface roughness. For attached flow, Wazzan et al.

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