in this paper we demonstrate the existence of a set of polynomials pi , 1 i  n , which arepositive semi-definite on an interval [a , b] and satisfy, partially, the conditions of polynomials found in thelagrange interpolation process. in other words, if a  a1  an  b is a given finite sequence of realnumbers, then pi (a j )  ij (ij is the kronecker delta symbol ) ; moreover, the sum of ...

The airfoil equation is considered over two disjoint intervals. Assuming the distance between the intervals is small an approximate solution is found and relationships between this approximation and the solution of the classical airfoil equation are obtained. Numerical results show the convergence of the solution of the original problem to the approximation. Polynomial solutions for an approxim...

Previous theories and empirical formulas for the lift of flat planing surfaces are reviewed, and the resemblance of the planing surface to the airfoil noted. A simple expression, which converges to the correct limits for exactly known cases, is assumed for the ratio of planing to airfoil lift, and the planing lift is then estimated by using airfoil experimental data. The resulting calculated va...

Detailed knowledge of local external heat transfer around a turbine airfoil is critical for an accurate prediction of metal temperature and component life. This paper discusses the results of measurements of the local gas side heat transfer coefficient distribution which were performed in an annular gas turbine vane hot-cascade test facility and provides comparisons with analytical predictions....

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....