Structural Design of Small-Scale Wind Turbine Blades

Abstract

This paper presents the structural design and experimental validation of three small-scale composite wind turbine blade configurations for Sri Lankan wind conditions with mean velocities of 6 m/s. Three 1.1 m GFRP blades sharing identical aerodynamic geometry but differing in skin construction, a bare hollow shell (B1), a sandwich-skin variant with a polyester core mat interlayer (B2), and a foam-filled shell (B3), were analyzed using an Euler Bernoulli beam model with span-varying flexural rigidity derived from Classical Lamination Theory and integrated numerically via a fourth-order Runge–Kutta scheme. Predicted flapwise tip deflections of 16.23 mm, 24.93 mm, and 16.18 mm for B1, B2, and B3, respectively, were validated against static load tests using a distributed 145 N aerodynamic load, with experimental deviations within 10% for all configurations. A key finding is that internal core material exerts negligible influence on flapwise stiffness at this blade scale, B1 and B3 deflect within 0.4% of each other, confirming that foam fill primarily provides anti-buckling support rather than bending rigidity. All blades satisfy the IEC 61400-2 tip deflection limit by a substantial margin.