面向扑翼翼面运动参数的优化设计

Optimal design of motion parameters of flapping wing

扑翼机的飞行依赖于扑翼翼面的运动,经过优化的运动策略能够使特定翼面发挥最佳的气动性能。然而目前扑翼机设计中缺乏有效的运动参数优化方法,无法针对给定机翼确定一组最优运动参数。采用非定常涡格法(UVLM)计算扑翼气动力,与现有的实验数据进行对比,验证了气动力计算方法的准确性。基于DIRECT(矩形分割)全局优化算法,以最大化推进效率为特定优化目标,对扑翼运动参数进行了迭代优化。结果表明,通过该优化算法能够得到最优扑翼运动参数,有效提高特定气动性能;应用优化算法计算得到的平均推力与基准运动的平均推力相比,在数值上有1.04倍的提高。在设计过程中,降低气动力约束有利于扑翼运动优化,使给定扑翼翼面具有更大的推进效率,无气动力约束的最大推进效率与基准运动的推进效率相比提高了46.8%。

The flight of an ornithopter depends on the motions of the flapping wing.The optimal aerodynamic characteristics of a specific flapping wing will be obtained when using an optimized motion strategy.Furthermore,it provides a design basis for the transmission mechanism of a flapping wing aircraft.However,there is currently a lack of effective method for motion optimization in design stage to determine a set of optimal motion parameters for a given wing.In this paper,the unsteady vortex lattice method(UVLM)is applied to calculate the aerodynamic effect caused by the flapping motion.To verify accuracy of the aerodynamic calculation method,the result is correctly compared with existing experiment data.Then based on the DIRECT(divide rectangle)global optimization algorithm,the flapping kinematics parameters are iteratively optimized to maximize the propulsion efficiency.The results show that the optimization method can effectively solve the optimal parameters of flapping kinematics parameters and improve specific aerodynamic performance.The average thrust calculated by the optimization algorithm in this paper has a 104%numerical improvement compared to that of the baseline motion.Besides,it indicates that reducing the lift and thrust constraints are beneficial to the optimization to achieve a higher propulsion efficiency in the design process.The maximum propulsion efficiency without aerodynamic constraints in this paper is improved by 46.8%compared to that of the baseline motion.