摘要
自然界中的昆虫和鸟类大都采用拍翼飞行的策略,其优越的气动表现使拍动飞行方式备受关注.值得注意的是,拍动飞行昆虫和鸟类在实现高机动性的同时,产生的噪音并不十分显著.因此,对拍翼飞行的流固声耦合问题进行研究,揭示其飞行动力学和声学特性,对于应用这类飞行技术具有重要的指导意义.文章采用一种浸入边界法对拍翼悬停时的流固声耦合问题进行数值模拟研究.具体针对刚性拍翼和不同刚度、质量比的柔性拍翼进行了数值模拟,分析了拍翼刚度和质量比对拍翼悬停时的升力和声学特性的影响.结果表明拍翼的转动能有效增加升力,提高效率并降低拍翼运动产生的声音;同时悬停拍翼的近场声受涡的影响明显,尤其是在较大的转动角度时;引入适当的弹性可有效提高拍翼在悬停时的气动表现,包括提高升力系数和效率;综合考虑气动和声学表现,可以看出当无量纲拍动频率在0.3~0.4时,低质量的拍翼(拍翼-流体质量比为1.0)产生的声音较小,同时又具备较高的效率.
Flapping flight strategy is widely adopted by insects and birds,which has drawn considerable attentions due to its high performance.It is worth noting that the good performance and great agility are also achieved with low noise.To apply this flight strategy to engineering,it is necessary to conduct corresponding study to understand both the aerodynamics and acoustics of the flapping wing.In this paper,an immersed boundary method was used to numerically study the sound generation by flapping wings in hovering flight.Both rigid and flexible wings were considered.The flexibility and structure-to-fluid mass ratio were varied to study their effects on the aerodynamics and acoustics.The results show that the rotating motion of the flapping wing can increase the lift and efficiency,and reduce the sound generation.The near field sound generated by the flapping wing in hovering flight is significantly influenced by the vorticity shed from the wing,especially at larger rotating amplitude.A medium flexibility improves the aerodynamic performance,i.e.,increasing the lift generation and efficiency.In addition,it is found that a lower sound can be achieved at a structure-to-fluid mass ratio of 1.0 and dimensionless flapping frequency of 0.3~0.4 with the high efficiency conserved.
作者
王力
田方宝
WANG Li;TIAN Fang-bao(University of New South Wales, Canberra 2600, Australia)
出处
《气体物理》
2020年第4期21-30,共10页
Physics of Gases
基金
澳大利亚研究理事会资助项目(DE160101098)。
关键词
弹性拍翼
流固声耦合
浸入边界法
气动声学
有限差分法
flexible flapping wing
fluid-structure-acoustics interaction
immersed boundary method
aeroacoustics
finite difference method
