The extremely thick blade root airfoils of the modern megawatt-scale wind turbines are prone to having sharp stall characteristics with associated unsteady aerodynamic blade loading and fatigue. With current technology designs reaching 45% thickness, these thick airfoils are incapable of producing high lift, and as a consequence they are aerodynamically and structurally sub-optimal. A computati...

In this paper, optimal airfoil shapes are found through manipulation of the velocity distribution by a genetic algorithm. The airfoil geometries are generated by an inverse method from velocity distribution parameters, and a viscous-flow analysis code is used to determine proper fitness values for candidate airfoils based on preset performance criteria. The method is compared with the more trad...

More than 100 research articles have referred to an experimental study by Feldkamp (1987) on the California sea lion, which mentions that its body resembles a symmetric airfoil, NACA 66018. We believe that perhaps an oversimplification has been made in this comparison. This conclusion may be arrived at by shifting the leading and trailing edges of the contour of the sea lion in order to move th...

More than 100 research articles have referred to an experimental study by Feldkamp (1987) on the California sea lion, which mentions that its body resembles a symmetric airfoil, NACA 66018. We believe that perhaps an oversimplification has been made in this comparison. This conclusion may be arrived at by shifting the leading and trailing edges of the contour of the sea lion in order to move th...

The present study addresses the experimental and numerical verification of the performance of a new airfoil design for lift driven vertical-axis wind-turbines (VAWT). The airfoil is obtained by a genetic algorithm optimization of the objective function proposed by Simão Ferreira and Geurts [19], which optimizes the aerodynamic performance of airfoils having a relatively larger thickness, provid...

Experimental studies on static, non-flapping dragonfly wings have shown favorable aerodynamic performance at low Reynolds number (Re ≤ 10,000). High lift is hypothesized to arise from the dragonfly’s pleated wing structure. A numerical study of flow past a modeled dragonfly wing section as well as its comparison to a corresponding profiled airfoil and a flat plate were conducted at Re = 10,000....

An experimental study was conducted to investigate the aerodynamic characteristics of a NASA low speed GA(W)-1 airfoil at the chord Reynolds number of ReC=160,000. Aerodynamic hysteresis was observed for the angles of attack close to the static stall angle of the airfoil. In addition to mapping surface pressure distribution around the airfoil, a high-resolution PIV system was used to make detai...

Numerical simulations of a two-dimensional airfoil, controlled by an applied moment in pitch and an airfoil controlled by jets, were investigated. These simulations couple the Reynolds-averaged Navier-Stokes equations and Euler's equations of rigid body motion, with an active control system. Controllers for both systems were designed to track altitude commands and were evaluated by simulating a...

This article presents application of an adjoint method to the aerodynamic shape optimization of deflector vanes installed in the fan nozzle of a turbofan engine. The purpose of the vanes is to reduce jet noise radiated towards the community, and the specific application of this study is for a supersonic turbofan engines with bypass ratio 2.7. The cost function used in the optimization includes ...

The unsteady wake of an EPPLER 361 airfoil in pitching motion has been investigated in a subsonic wind tunnel by hot-wire anemometry. The airfoil was given the pitching motion about the one-quarter chord axis at reduced frequency of 0182. Streamwise mean velocity profiles (wake profiles) were investigated at several vertically aligned points behind the airfoil at one-quarter chord downstream di...