Optimization of a carbon fiber composite blade of a counter-rotating fan for aircraft engines

Abstract

Achieving higher efficiency and less weight is the most important target for future engine development. New lightweight materials like fiber reinforced composites should be applied for the fan blading to reduce the weight. The aerodynamic efficiency should be improved simultaneously. A method that achieves both targets is presented in this paper. This method was carried out on the counter-rotating integrated shrouded propfan (called CRISP), which is a possible future fan concept for ultra-high bypass ratio engines (Görke et al., 2012). The underlying paper investigates the effects of a numerically optimized multi-ply composite for a given application of a fan blade on its aerodynamic and structural mechanical properties. To determine the effects of different multi-ply composite structures, two structural mechanical preliminary studies with different materials are performed, whereby only the first of the two rotors is considered and the blade geometry remains fixed. Both studies, one with a symmetrical multi-ply structure and the other with a completely free multi-ply composite, showed big advantages through adapted fiber alignments in the optimized multi-ply composites. In a subsequent multidisciplinary optimization with CFD and FEM calculation processes of the complete fan stage, both, the parameters of the 3D blade geometry and the fiber alignments were free. Hence, it was possible to examine the effect of the free parameters in the fiber alignment on the aerodynamic and mechanical potential.