Computational Investigation of Twist Morphing Rotor Blades for Aerodynamic Efficiency Enhancement

Abstract

The aerodynamic performance of rotorcraft blades plays a pivotal role in determining rotor system efficiency; directly impacting lift generation, fuel consumption, and mission endurance. Conventional rotor designs, constrained by fixed blade geometries, impose inherent limitations on optimising aerodynamic efficiency across varying flight conditions. This study investigates the feasibility of twistmorphing rotor blades, wherein a full-chord twist technique is introduced to enhance aerodynamic performance. A high-fidelity computational fluid dynamics (CFD) analysis was conducted using highperformance computing (HPC) infrastructure (SimScale) across 10 case studies to evaluate the aerodynamic effects of this morphing technique on a baseline Sea King rotor blade. The analysis investigated a spanwise section of 0.85 r/R (where r/R represents the spanwise blade position normalised by radius), with twist angles varying from -14° to +14°. A RANS steady-state solver (k-omega SST) was employed for cruise and hover conditions, with velocity-pressure coupling. In hover mode, the greatest increase in CL/CD was observed when a linear +10° was applied to the morphing section, improving the aerodynamic efficiency by 6.3%. At cruise conditions, the highest increase in aerodynamic efficiency was observed at +14° where the CL/CD improved by 31%. The findings validate twist morphing as a viable mechanism for aerodynamic enhancement, demonstrating its potential to improve rotorcraft performance. The insights provide a quantitative foundation for integrating morphing rotor technology into the next generation of rotorcraft engineering. While the aerodynamic benefits are evident, future research must address aeroelastic modelling, structural dynamics, and real-time actuation feasibility to ensure practical implementation in the future rotary-wing aircraft.