General considerations and conclusive remarks are presented after the discussion.Ĭompared with traditional underwater equipment powered by propeller, the manta-ray-inspired vehicle with MPF mode (Median fin/paired fin) has the advantages of stable swimming attitude, high maneuverability, and low noise, etc. It contains a discussion on the current prospects and challenges faced by these devices, along with a comparative analysis centered on their aerodynamic controllability. This review performs a comprehensive and up‐to‐date literature survey of selected flow‐control devices, from their time of development up to the present. Development and optimization of flow‐control devices present the potential for reduction in the COE, which is a major challenge against traditional power sources. These flow‐control devices are operated primarily under two schemes: passive and active control. Flow‐control mechanisms feature the ability to effectively enhance/suppress turbulence, advance/delay flow transition, and prevent/promote separation, leading to enhancement in aerodynamic and aeroacoustics performance, load alleviation and fluctuation suppression, and eventually wind turbine power augmentation. Introduction of flow‐control devices on the wind turbine is a plausible solution to this issue. Accordingly, this demands higher overhaul‐and‐maintenance (O&M) costs, leading to higher cost of energy (COE). However, the fact that massive turbine blades inherently experience increased fatigue and ultimate loads is no secret, which compromise their structural lifecycle. Such growth in the industry has been accompanied by the desirability and demand for larger wind turbines aimed at harnessing more power. It is projected that, in the following years, the wind‐energy industry will maintain its rapid growth over the last few decades. Because the end plates were finite, strong tip vortices were still observed even though they were modified by the end plates.

Two finite end plates (18 13 in:) were attached at the wing section tips, serving the support for the model and reducing the three-dimensionality of flow. The chord and span of the model are 10 and 12 in., respectively. The Gurney flap height ranged from 1.2 to 6:75%c.

The main wing was a ceramic NACA0012 airfoil section and a six-component internal force balance was used to measure the aerodynamic forces. To provide additional data, particularly for higher Gurney flaps, we conducted Gurney flap measurements for the chord Reynolds number 6 10 5 in the Advanced Design Wind Tunnel of Western Michigan University. Three sets of data for the symmetrical main airfoils (NACA0011 and NACA0012) are used, whereas others are used for the cambered main airfoils. These data are collapsed into a single square-root function of h=c as predicted by Eq. Expressions for the thickness functions, thickness/chord ratios, and leading-edge radii of elliptic, Joukowski, and biconvex airfoils are tabulated.Compares the normalized lift enhancement C l =q h=c p with the experimental and CFD results, where the factor q depending on the model geometry and test conditions is adjusted to fit the results obtained in different measurements and numerical calculations. For airfoils closed at both ends, for rounded edges, and for sharp edges. Conditions that the constants An and Bm must satisfy the following conditions. Contrary to implications of previous studies, it is shown that the thickness function will contain cosine terms whenever a sharp edge is present and sine terms whenever a rounded edge is involved. An analytical closed-form solution to the transformed equation that must be solved for the thickness problem in thin-airfoil theory is obtained by expanding the airfoil thickness function in a trigonometric series.

Thin airfoil theory