Aerodynamics of Wind Turbines

Abstract

The study of rotor blade aerodynamic performances of wind turbine has been presented in this thesis. This study was focused on aerodynamic effects changed by blade surface distribution as well as grid solution along the airfoil. The details of numerical calculation from Fluent were described to help predict accurate blade performance for comparison and discussion with available data.The direct surface curvature distribution blade design method for two-dimensional airfoil sections for wind turbine rotors have been discussed with the attentions to Euler equation, velocity diagram and the factors which affect wind turbine performance and applied to design a blade geometry close to an existing wind turbine blade, Eppler387, in order to argue that the blade surface drawn by direct surface curvature distribution blade design method contributes aerodynamic efficiency.The FLUENT calculation of NACA63-215V showed that the aerodynamic characteristics agreed well with the available experimental data at lower angles of attack although it was discontinuities in the surface curvature distributions between 0.7 and 0.8 in x/c. The discontinuities were so small that the blade performance could not be affected.The design of Eppler 387 blade performed to reduce drag force. The discontinuities of surface distribution matched the curve of the pressure coefficients. It was found in the curvature distribution that the leading edge pressure side had difficulties to connect to Bezier curve and also the trailing edge circle was never be tangent to the lines of trailing edge pressure and suction sides due to programming difficulties.

How does turbulence change approaching a rotor?

“…We find a slope deviating 1% from one and a correlation coefficient of 0.98. The scatter is larger than other similar comparisons (see for example Sathe et al,10 2015, figure 4). Due to the yawing of the turbine, the measurements are rarely collocated.…”

The impact of the diurnal cycle of the atmospheric boundary layer on physical variables relevant for wind energy applications

“…This results in a larger gradient of the forces acting on the blades at 490 individual heights during the SBL phase, as F ≈ u 2 following Hansen (2008). The vertical gradient in the active force leads to an asymmetric fatigue loading of a wind turbine at night, which has an effect on e.g.…”

Implementation of the Kdamper Concept to Wind Turbine Towers

“…( ) bl c r is the chord of the blade profile varying along the blade length r, the distribution of which is obtained from [18], [12]. In order to evaluate ( ) N C r , the classical Blade Element Momentum theory [9] …”