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种子叶片自旋下落过程涡系的PIV实验研究

董林 温国安 雷紫薇 李鹿辉

董 林,温国安,雷紫薇,等. 种子叶片自旋下落过程涡系的PIV实验研究[J]. 实验流体力学,2021,35(5):54-60 doi: 10.11729/syltlx20200004
引用本文: 董 林,温国安,雷紫薇,等. 种子叶片自旋下落过程涡系的PIV实验研究[J]. 实验流体力学,2021,35(5):54-60 doi: 10.11729/syltlx20200004
DONG L,WEN G A,LEI Z W,et al. PIV experimental study on vortex structures induced by free autorotation fall of a samaras[J]. Journal of Experiments in Fluid Mechanics, 2021,35(5):54-60. doi: 10.11729/syltlx20200004
Citation: DONG L,WEN G A,LEI Z W,et al. PIV experimental study on vortex structures induced by free autorotation fall of a samaras[J]. Journal of Experiments in Fluid Mechanics, 2021,35(5):54-60. doi: 10.11729/syltlx20200004

种子叶片自旋下落过程涡系的PIV实验研究

doi: 10.11729/syltlx20200004
基金项目: 国家自然科学基金(11721202,11772035)
详细信息
    作者简介:

    董林:(1985-),女,上海人,讲师,博士。研究方向:颗粒流动控制,生物流体控制。通信地址: 上海市龙腾路333号实训楼4303(201620)Email:donglin16@163.com

    通讯作者:

    E-mail:donglin16@163.com

  • 中图分类号: V211.7; O357

PIV experimental study on vortex structures induced by free autorotation fall of a samaras

  • 摘要: 本文利用粒子图像测速技术研究种子叶片自由旋转下落过程中不同涡系的相互作用机理。以典型枫树种子叶片为研究对象,通过对比不同叶片长度、叶面厚度、叶面宽度、下落锥角、自旋角速度、下落速度和下落初始角度等参数对过渡期和稳定期的影响,分析了诱发叶片自旋的外形特征和空间特性。结合特征参数分析,对叶片自旋稳定期开展了PIV流场测量实验,解析了无干扰下种子叶片下落过程中涡系的产生和演化机理。实验结果表明:稳定期气流在叶尖正面位置产生前缘涡(沿展向呈圆锥状结构),后缘位置产生反方向的后缘涡;两个涡发生相互耦合运动,前缘涡的强度大于后缘涡,从而导致叶面产生锥角。在前缘和叶尖前方观测到较高的速度向上的区域,而在后缘和叶根附近则出现较高的速度向下的区域,从而对种子产生向上的升力,使叶片实现自旋稳定下落。通过枫叶种子自由下落的无干扰PIV测量,初步获得了贴近叶片表面前缘涡的运动性状,验证了后缘涡的存在,结论对单翼型旋转叶片的设计有一定指导意义。
  • 图  1  带有丰富叶脉结构的果叶及自旋下落俯视状态

    Figure  1.  Maple samaras with vein structure and the top view of auto-rotation fall

    图  2  测量种子自旋下落的实验装置和参数

    Figure  2.  Experimental setup and measurement methods for free auto-rotation fall of maple samaras and parameters

    图  3  PIV实验系统示意图

    Figure  3.  Schematic diagram of the PIV experimental system

    图  4  枫树种子横向断面的瞬时流场结构

    Figure  4.  Instantaneous flow structures on the cross section of maple samara

    图  5  枫树种子展向断面的瞬时流场结构

    Figure  5.  Instantaneous flow structures on the span section of maple samara

    图  6  种子横向断面的瞬时流场结构

    Figure  6.  Instantaneous flow structures on the cross sections of maple samara

    图  7  枫树种子涡系运动机理

    Figure  7.  Motion mechanism of maple samara vortexes

    表  1  枫树种子平均外形特征参数统计

    Table  1.   Average shape characteristic parameters of maple samaras

    类型叶弦长
    L/mm
    叶面最大宽度
    b/mm
    叶面平均厚度
    k/mm
    果实厚度
    t/mm
    种子质量
    M/mg
    小型 17.3 5.7 0.2 3.8 47.0
    中型 20.0 6.7 0.2 4.0 49.3
    大型 22.7 8.7 0.2 4.0 52.0
    下载: 导出CSV

    表  2  典型中型枫树种子表面平均特征参数

    Table  2.   Average parameters of typical surface characteristics

    叶弦长
    L/mm
    平均叶脉
    数量
    叶面平均
    厚度k/mm
    叶凹凸幅度/
    mm
    叶凹凸高度/
    mm
    前缘厚度/
    mm
    20.0700.20.150.180.53
    下载: 导出CSV

    表  3  枫树种子在稳定期中自旋运动的平均特性参数

    Table  3.   Average parameters of maple samaras in falling

    类型雷诺数
    Re
    下落锥角
    β/(°)
    下落速度
    V/(m·s–1
    自旋角速度
    ω/(rad·s–1
    过渡期距离/
    cm
    小型19 30016.201.1245.0032.00
    中型22 51022.611.1334.1433.75
    大型21 48026.450.9519.0033.00
    下载: 导出CSV
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出版历程
  • 收稿日期:  2020-01-03
  • 修回日期:  2020-08-26
  • 网络出版日期:  2021-11-15
  • 刊出日期:  2021-10-25

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