Design of high speed proprotors using multiobjective optimization techniques

A multidisciplinary optimization procedure is developed for the design of high speed proprotors. The objectives are to simultaneously maximize the propulsive efficiency in high speed cruise and the rotor figure of merit in hover. Since the problem involves multiple design objectives, multiobjective function formulation techniques are used. Two different multiobjective function procedures, the Kreisselmeier-Steinhauser function approach and the Minimum Sum 13 approach, are used. A detailed two-celled isotropic box beam is used to model the load carrying member within the rotor blade. Constraints are imposed on rotor blade aeroelastic stability in cruise, the first natural frequency in hover and total blade weight. Both aerodynamic and structural design variables are used. The results obtained using both objective function formulations are compared to the reference rotor and show significant aerodynamic performance improvements without sacrificing dynamic and aeroelastic stability characteristics. The procedure developed provides significant design trends and trade-off information associated with the two conflicting design objectives.