Air Force Research Laboratory, Munitions Directorate, Eglin Air Force Base, FL 32542, USA.
Bioinspir Biomim. 2010 Mar;5(1):16002. doi: 10.1088/1748-3182/5/1/016002. Epub 2010 Feb 16.
Biologists have shown that bat wings contain distributed arrays of flow-sensitive hair receptors. The hair receptors are hypothesized to feedback information on airflows over the bat wing for enhanced stability or maneuverability during flight. Here, we study the geometric specialization of hair-like structures for the detection of changes in boundary layer velocity profiles (shapes). A quasi-steady model that relates the flow velocity profile incident on the longitudinal axis of a hair to the resultant moment and shear force at the hair base is developed. The hair length relative to the boundary layer momentum thickness that maximizes the resultant moment and shear-force sensitivity to changes in boundary layer shape is determined. The sensitivity of the resultant moment and shear force is shown to be highly dependent on hair length. Hairs that linearly taper to a point are shown to provide greater output sensitivity than hairs of uniform cross-section. On an order of magnitude basis, the computed optimal hair lengths are in agreement with the range of hair receptor lengths measured on individual bat species. These results support the hypothesis that bats use hair receptors for detecting changes in boundary layer shape and provide geometric guidelines for artificial hair sensor design and application.
生物学家已经证明，蝙蝠的翅膀上分布着一系列对气流敏感的毛发感受器。这些毛发感受器被假设为能够反馈蝙蝠翅膀上的气流信息，以提高飞行时的稳定性或机动性。在这里，我们研究了毛发状结构的几何专业化，以用于检测边界层速度剖面（形状）的变化。我们开发了一种准稳态模型，该模型将作用于毛发纵轴的流动速度剖面与毛发根部的总力矩和剪切力相关联。确定了相对于边界层动量厚度的毛发长度，该长度使总力矩和剪切力对边界层形状变化的灵敏度最大化。结果表明，总力矩和剪切力的灵敏度高度依赖于毛发长度。线性渐缩到一点的毛发比具有均匀横截面的毛发提供更大的输出灵敏度。在数量级上，计算出的最佳毛发长度与在单个蝙蝠物种上测量的毛发感受器长度范围一致。这些结果支持了蝙蝠使用毛发感受器来检测边界层形状变化的假设，并为人工毛发传感器的设计和应用提供了几何指南。
