Design of HALE Propeller through Multi-objective Optimization

Abstract

HALE (high-altitude long-endurance) aircrafts, relatively novel, unmanned air vehicles specifically designed to fly at high altitudes for extended periods of time, require state-of-theart technological solutions in order to operate properly. Likewise, their propulsion system (that usually implies propelled flight) should be optimized with respect to both aerodynamic and structural aspects. This paper presents a conceptual design of a HALE propeller realized through multi-objective and multidisciplinary optimization procedure. A tightly coupled aerostructural two-criteria optimization by genetic algorithm is performed to define a laminated blade of best aerodynamic performance (expressed through maximal aerodynamic efficiency) and minimal mass that is both statically and dynamically reliable when subjected to conjugate aerodynamic, inertial and gravitational loads while cruising at the altitude of 20 km. Numerous geometric, aerodynamic and structural constraints are introduced, and different materials and laminate lay-up sequences are considered. Obtained Pareto sets (of optimal solutions) and Pareto fronts are presented and analyzed in detail. In the end, some recommendations and further research possibilities are given.