This paper presents an integrated method for designing airfoil families of large wind turbine blades. For a
given rotor diameter and a tip speed ratio, optimal airfoils are designed based on the local speed ratios.
To achieve a high power performance at low cost, the airfoils are designed with the objectives of high Cp
and small chord length. When the airfoils are obtained, the optimum flow angle and rotor solidity are
calculated which forms the basic input to the blade design. The new airfoils are designed based on a
previous in-house designed airfoil family which was optimized at a Reynolds number of 3 million. A
novel shape perturbation function is introduced to optimize the geometry based on the existing airfoils
which simplifies the design procedure. The viscous/inviscid interactive code XFOIL is used as the aerodynamic
tool for airfoil optimization at a Reynolds number of 16 million and a free-stream Mach number
of 0.25 near the tip. Results show that the new airfoils achieve a high power coefficient in a wide range of
angles of attack (AOA) and are extremely insensitive to surface roughness. Finally, a full blade analysis
using computational fluid dynamics (CFD) and blade element momentum (BEM) technique proves the
reliability of the integrated design method.