论文标题
生物风格的被动部署瓣的流体结构相互作用，以增强升降机
Fluid-structure interaction of a bio-inspired passively deployable flap for lift enhancement
论文作者
论文摘要
鸟类具有出色的能力，可以在后置攻击角度进行复杂的动作。进行此类操作的同时，自我施加秘密羽毛的被动部署是对这些空气动力学能力的被动流控制范式的反应。大多数涉及秘密fe依的被动流控制的研究都将羽毛建模为刚性附着或在机翼上自由移动的皮瓣。通过扭转弹簧安装的襟翼使配置更具象征性的与秘密羽毛动态相关的有限刚度。与此更普遍的情况相关的性能益处和流动物理学仍然在很大程度上尚未探索。在这项工作中，我们将覆盖羽毛模拟为一种可被部署的，扭转的铰链襟翼，上面是固定机翼的吸气表面。我们以低雷诺数为$ re = 1 {，} 000 $和$ 20^\ circ $的$ re = 1 {，} 000 $的$ reynolds数量研究此机翼 - 弗拉普系统，并使用基于投影的沉浸式边界方法进行高保真非线性模拟。通过改变弹簧的刚度，皮瓣的质量和铰链位置进行的一项参数研究，相对于基线无皮瓣的病例，提升的提高高达27％，并揭示了两个主要的流动行为状态。一项详细的分析表明，刚度依赖性的平均皮瓣挠度和惯性依赖性振幅和瓣振荡的相改变了这两个方案中的主要流动特性。性能益处特别感兴趣的是皮瓣参数，可增强升力功能的前沿涡旋，同时削弱尾随边缘涡流以及上游反向流的上游传播的有害效应。这些参数还产生了在这两个制度中与涡旋脱落过程的瓣振荡的有利的时间同步。
Birds have a remarkable ability to perform complex maneuvers at post-stall angles of attack. The passive deployment of self-actuating covert feathers in response to unsteady flow separation while performing such maneuvers provides a passive flow control paradigm for these aerodynamic capabilities. Most studies involving covert-feathers-inspired passive flow control have modeled the feathers as a rigidly attached or a freely moving flap on a wing. A flap mounted via a torsional spring enables a configuration more emblematic of the finite stiffness associated with the covert-feather dynamics. The performance benefits and flow physics associated with this more general case remain largely unexplored. In this work, we model covert feathers as a passively deployable, torsionally hinged flap on the suction surface of a stationary airfoil. We numerically investigate this airfoil-flap system at a low Reynolds number of $Re=1{,}000$ and angle of attack of $20^\circ$ by performing high-fidelity nonlinear simulations using a projection-based immersed boundary method. A parametric study performed by varying the stiffness of the spring, mass of the flap and location of the hinge yielded lift improvements as high as 27% relative to the baseline flap-less case and revealed two dominant flow behavioral regimes. A detailed analysis revealed that the stiffness-dependent mean flap deflection and inertia-dependent amplitude and phase of flap oscillations altered the dominant flow characteristics in both the regimes. Of special interest for performance benefits were the flap parameters that enhanced the lift-conducive leading-edge vortex while weakening the trailing-edge vortex and associated detrimental effect of upstream propagation of reverse flow. These parameters also yielded a favorable temporal synchronization of flap oscillations with the vortex-shedding process in both regimes.
