Aeronautical Engineering: A special bibliography with indexes, supplement 48

This special bibliography lists 291 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1974

Aeronautical Engineering. A continuing bibliography, supplement 115

This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1979

Vibration characteristic analysis and optimization of rotor hub for helicopters based on genetic algorithm

The aero-elastic response of the blades is affected by the structure style of the rotor hub. The fatigue life of the structure and the vibration level of the entire helicopter are directly affected by the aero-elastic response of the blades. Therefore, its vibration characteristics and aero-elastic response shall be considered emphatically during structure design. The flapping and lead-lag characteristics of the rotor hub were tested experimentally in the paper. It was shown in results that a big vibration displacement was generated from the rotor hub under two working conditions. However, a larger vibration displacement was generated from the flapping than that of the lead-lag. Therefore, it is necessary to conduct optimization design to the rotor hub. Analysis was carried out to aero-elastic dynamics of bearing-less rotor. Afterwards, a multi-objective optimization model for reducing vibration and aero-elastic dynamic of bearing-less rotor was built. Pareto front of multi-objective optimization design for bearing-less rotor was acquired by Genetic Algorithm (GA). To reduce the optimization burdens, the aero-elastic dynamic model was replaced by Radial Basis Function (RBF) model during the optimization. To decrease the computational costs, the sample points with the minimum point set center deviation of the current surrogate model were added gradually. Meanwhile, the design schemes of Pareto front were ranked by TOPSIS to select the design scheme with the maximum satisfaction. Comparison was carried out between the rotor design scheme with the maximum satisfaction and the unoptimized model in terms of modal frequency, modal shape and vibration load of the hub. The results showed that the dynamic performance of the optimized rotor was improved significantly. The method in this paper also provided an important reference for multi-objective optimization of aero-elastic dynamic and engineering design of other rotors

Multifidelity Aerodynamic Optimization of a Helicopter Rotor Blade

International audienceAmultifidelity optimization technique is applied to the design of a helicopter rotor blade to improve its performance in forward flight. This optimization technique is based on a surrogate model that replaces the high-fidelity computational fluid dynamics (CFD)/computational structural dynamics (CSD) simulations necessary to capture the three-dimensional unsteady effects generated in the flowfield of a complex blade geometry. The single low-fidelity model based on kriging methodology and generated by lifting-line simulations leads to a power benefit of 2.5%, which is not reproducible by an a posteriori high-fidelity CSD/CFD computation. The optimization procedure using cokriging surrogate models based on two levels of fidelity (lifting-line and CSD/CFD simulations) leads to a realistic blade planform, for which the power benefit is estimated at 2.2%. This optimized solution, obtained after a factor-ofsix reduction in CPU time, shows the advantages of using a cokriging surrogate model (rather than a single-fidelity kriging model) for aerodynamic optimizations

Aeronautical Engineering: A special bibliography, supplement 60

This bibliography lists 284 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1975

Characterization of Quantum Derived Electronic Properties of Molecules: A Computational Intelligence Approach

Series: Lecture Notes in Computer Scienc

State-of-the-art in aerodynamic shape optimisation methods

Aerodynamic optimisation has become an indispensable component for any aerodynamic design over the past 60 years, with applications to aircraft, cars, trains, bridges, wind turbines, internal pipe flows, and cavities, among others, and is thus relevant in many facets of technology. With advancements in computational power, automated design optimisation procedures have become more competent, however, there is an ambiguity and bias throughout the literature with regards to relative performance of optimisation architectures and employed algorithms. This paper provides a well-balanced critical review of the dominant optimisation approaches that have been integrated with aerodynamic theory for the purpose of shape optimisation. A total of 229 papers, published in more than 120 journals and conference proceedings, have been classified into 6 different optimisation algorithm approaches. The material cited includes some of the most well-established authors and publications in the field of aerodynamic optimisation. This paper aims to eliminate bias toward certain algorithms by analysing the limitations, drawbacks, and the benefits of the most utilised optimisation approaches. This review provides comprehensive but straightforward insight for non-specialists and reference detailing the current state for specialist practitioners

Aeronautical engineering: A continuing bibliography with indexes (supplement 278)

This bibliography lists 414 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1992