高度可变形的折叠膜翅膀可以抑制悬浮中的前沿,以获得更好的性能
Alexander Gehrke1, Karen Mulleners1
1École polytechnique fédérale de Lausanne, School of Engineering, Institute of Mechanical Engineering, Unsteady Flow Diagnostics Laboratory, Lausanne 1015, Switzerland.
概括
高度灵活的翅膀,如蝙蝠的翅膀,可能不会形成前沿. 相反,它们通过结合的剪切层实现了增强的升力和能源效率,与昆虫的飞行机制不同.
科学领域:
- * 流体动力学和生物启发工程.
- * 昆虫和蝙蝠飞行的空气动力学.
背景情况:
- * 昆虫利用前沿 (LEVs) 在飞行时增强提升力.
- * 昆虫的翅膀是刚性的膜,与蝙蝠的高度变形的翅膀不同.
研究的目的:
- * 调查LEVs在高度可变形的膜翼中的作用.
- * 了解翅膀的灵活性如何影响旋形成和空气动力学性能.
- * 探索灵活的翅膀中的替代提升生成机制.
主要方法:
- * 在流体动力学负荷下对可变形膜翼进行实验研究.
- * 分析机翼变形,旋转和空气动力学力.
- *缩放分析和流量状态指标 (几何角度) 的识别.
主要成果:
- * 增加了翅膀的灵活性,抑制了连贯的前边 vortex 的形成.
- * 在最佳的有机弹性条件下,没有LEV,而是有边界剪切层.
- *可变形的机翼比刚性机翼实现更高的起重和能源效率.
结论:
- *灵活的膜翼可以在没有LEV的情况下实现高效的飞行.
- * 有界的剪切层是可变形翅膀中升起的关键机制.
- *这些发现可能解释小蝙蝠的高效悬浮,并为机器人飞行设计提供信息.
相关概念视频
Steady, Laminar Flow Between Parallel Plates
125
Understanding steady, laminar flow between parallel plates is essential for analyzing and designing flow in narrow rectangular channels, commonly found in various water conveyance and drainage systems. The Navier-Stokes equations govern fluid motion and are generally challenging to solve due to their nonlinearity. However, simplifications are possible in certain cases, like the steady laminar flow between parallel plates. For this scenario, we assume steady, incompressible, laminar flow.
125
Lift
38
Lift is a fundamental aerodynamic force that acts perpendicular to the direction of airflow. It plays a central role in achieving and sustaining flight and in stabilizing various vehicles. Lift primarily originates from pressure differences created across surfaces, such as an airfoil. A lower pressure region forms above the wing, while a higher pressure region forms below it, generating an upward force. This differential results from the shape and orientation of the airfoil, enabling the wing...
38
Turbulent Flow
132
Turbulent flow is characterized by unpredictable fluctuations in velocity and pressure, which result in a chaotic fluid movement distinct from the orderly patterns of laminar flow. While laminar flow is governed by smooth, parallel layers with minimal mixing, turbulent flow exhibits highly irregular, three-dimensional patterns. This behavior arises due to instabilities in the fluid's velocity profile, and amplifies as the flow velocity increases. Minor disturbances, known as turbulent...
132
Laminar Flow
584
Laminar flow represents a smooth, orderly fluid motion where particles move along parallel paths, resulting in minimal mixing between layers. Streamlined particle paths characterize this flow regime and occur under conditions where viscous forces dominate over inertial forces. The distinction between laminar, transitional, and turbulent flow is primarily determined by the Reynolds number, a dimensionless quantity calculated as:
584
Steady, Laminar Flow in Circular Tubes
139
Hagen-Poiseuille flow describes a viscous fluid's steady, incompressible flow through a cylindrical tube with a constant radius R. This flow profile is often applied to understand fluid transport in narrow channels, such as capillaries. It serves as a foundational example of laminar flow. In this model, cylindrical coordinates (r,θ,z) are used to describe the radial (r), angular (θ), and axial (z) dimensions within the tube. For Hagen-Poiseuille flow, the velocity profile is...
139
Boundary Layer Characteristics
28
When a fluid encounters a solid surface, a boundary layer forms due to the interaction between the fluid's motion and the stationary surface. This phenomenon is characterized by a thin region adjacent to the surface where viscous forces dominate, influencing the fluid's velocity profile. The development of the boundary layer begins at the leading edge of the surface and evolves as the fluid moves downstream.As the fluid flows over the surface, friction between the fluid and the wall slows down...
28


