Challenges in permeability characterisation for modelling the manufacture of wind turbine blades

As wind turbine blades continue to increase in size, and market competition grows, lean manufacturing has become even more important for OEMs. The rapid development of new blade designs, with greater performance, and reduced production waste are driving the need for predictive modelling of the blade infusion process. Such simulations are reliant upon Darcy’s Law for the description of fluid flow through porous materials and therefore depend greatly on the permeability properties of the blade preform materials. The characterisation of fabric permeability, although unstandardised, has been well studied in recent years as the focus of numerous international benchmarking efforts. However, the effective permeability properties of infusion consumables, core materials, and pre-cast elements are not so well defined or validated, despite their significance on infusion behaviour. Hence, the great variety of preform materials, stacking configurations, geometric features, and transition regions in wind turbine blades present considerable challenges in terms of permeability characterisation and subsequent modelling. This article reviews some of the challenges, opportunities, and alternatives for characterising permeability in common blade preform materials, along with examples of how these properties have been applied in numerical models to better simulate the resin infusion manufacturing process for wind turbine blades.