Indeterminacy of drag exerted on an arrow in free flight: arrow attitude and laminar-turbulent transition
Indeterminacy of drag exerted on an arrow in free flight: arrow attitude and laminar-turbulent transition
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自由飞行中箭头所受阻力的不确定性：箭头姿态和层流-湍流转变
DOI：
10.1088/1361-6404/aa8339
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发表时间：
2017
影响因子：
0.7
通讯作者：
H. Sugiura
中科院分区：
文献类型：
--
作者：
T. Miyazaki;T. Matsumoto;R. Ando;J. Ortiz;H. Sugiura
本文研究了箭体（A/C/E;伊斯顿）的气动特性，发现箭体上边界层的层流-湍流转捩发生在Re数为1.2 × 104 < Re < 2.0 × 104的范围内。在本文中，我们重点研究的影响，箭头的姿态的过渡。对两种类型的舵（自旋翼舵和燃气舵）进行了箭尾试验，并对它们的稳定效果进行了比较。进行了两次无支架干扰试验，以提供气动特性，如阻力、升力和俯仰力矩系数。静态空气动力学特性是在风洞中用JAXA的60 cm磁悬浮和天平系统测量的。当箭头与气流对齐时，Re < 1.5 × 104时，边界层保持层流状态; Re < 1.5 × 104时，阻力系数约为1.5。如果箭头与气流的迎角为0.75 °，则在Re = 1.1 × 104时，将发生向紊流的转变，阻力系数将增加到约3.1。此外，还进行了自由飞行实验。箭的速度和角速度是用五台高速摄像机记录下来的。通过分析记录的图像，我们得到的初始和最终的速度从阻力系数的确定。利用从视频图像中获得的初始数据，通过积分刚体的运动方程，数值计算自由飞行中箭的轨迹和姿态。当Re = 1.75 × 10 ~ 4时，如果最大攻角超过0.4°，边界层将发生层流-湍流转捩。初始角速度对攻角的关键影响也被检查。
The aerodynamic properties of an arrow (A/C/E; Easton) were investigated in an extension of our previous work, in which the laminar-turbulent transition of the boundary layer on the arrow shaft was found to take place in the Re number range of 1.2 × 104 < Re < 2.0 × 104. In this paper, we focus on the influence of the arrow’s attitude on the transition. Two types of vane (Spin Wing vane and Gas Pro vane) are fletched, and their stabilizing effects are compared. Two support-interference-free tests are performed to provide aerodynamic properties such as the drag, lift and pitching moment coefficients. The static aerodynamic properties are measured in a wind tunnel with JAXA’s 60 cm magnetic suspension and balance system. When the arrow is aligned with the flow, the boundary layer remains laminar for Re < 1.5 × 104, and the drag coefficient is approximately 1.5 for 1.0 × 104 < Re < 1.5 × 104. If the arrow has an angle of attack of 0.75 ° with the flow, the transition to turbulence takes place at approximately Re = 1.1 × 104, and the drag coefficient increases to approximately 3.1. In addition, free flight experiments are performed. The arrow’s velocity and angular velocity are recorded using five high-speed video cameras. By analysing the recorded images, we obtain the initial and final velocities from which the drag coefficient is determined. The trajectory and attitude of the arrow in free flight are computed numerically by integrating the equations of motion for a rigid body using the initial data obtained from the video images. The laminar-turbulent transition of the boundary layer is shown to take place, if the maximum angle of attack exceeds about 0.4° at Re = 1.75 × 104. The crucial influence of the initial angular velocity on the angle of attack is also examined.