Study about relation between fineness ratio dependency on drag of magnetically suspended axial cylinders and their wake structure

磁悬浮轴流圆柱细度比阻力依赖性与其尾流结构关系研究

• 批准号: 15560163
• 负责人: SAWADA Hideo
• 金额: $ 2.3万
• 依托单位: Japan Aerospace Exploration Agency
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560163/
• 关键词: drag; blunt body; magnetic suspension; separation; wake; reattachment; axial symmetric flow; axial cylinder

In this study, drag coefficients of axial cylinders with various fineness ratios were measured with the 60cm magnetic suspension and balance system at Japan Aerospace Exploration Agency which has the largest test section of low speed wind tunnel in the world. Besides, relation between the drag and wake structure dependency on its fineness ratio was also investigated. Obtained drag coefficients of the cylinders with fineness ratio ranged from 4 to 8 showed independent of Reynolds number from 50000 to 10000 based on model diameter. The boundary layer on the models are turbulent downstream the reattachment point of the separated flow at its leading edge. The fact of that drag coefficient depends on fineness ratio mainly causes the change of viscous friction drag by the turbulent boundary layer developed on the model downstream the reattachment point. We found that the drag coefficient gets its minimum value with respect to the fineness ratio from 1.2 to 4.0 and that the fineness ratio of … More the minimum drag coefficient ranges from 1.6 to 1.7. The minimum value looks smaller definitely than the published one and it is less than 0.8. However, we cannot point out one value because of blockage effect of bluff body which cannot be evaluated. We also measured base pressures of the cylinder with wireless technology without any support interference. The results showed that the base pressure coefficient gets its maximum value when the drag coefficient gets its minimum value. FFT analysis of the measured pressure fluctuations also showed definite peaks. Besides, we observed that centers of vortices on the axial cylinder wake cross sections move in non-axial-symmetric way instantaneously with PIV measurements. The observations were carried out without any support interference because we used the magnetic suspension and balance system. The flow in this study will be very sensitive on support systems and Ply measurement with the magnetic suspension is an ideal way of such kind of tests. Less

在这项研究中，日本航空航天勘探机构的60厘米磁悬架和平衡系统测量了具有各种细度比率的轴向圆柱的阻力系数，该机构具有世界上低速风洞的最大测试部分。此外，还研究了阻力和尾流结构对其细度比的关系。根据模型直径，获得的圆柱体的阻力系数为4到8，范围为4到8，独立于50000至10000。模型上的边界层在下游的湍流是其前缘分离流的保留点。该阻力系数的事实取决于细度比，主要导致粘性摩擦的变化，而在保留点下游的模型上开发的湍流边界层。我们发现，阻力系数相对于1.2到4.0的细度比，并且最小阻力系数的最小值为1.6至1.7。最小值看起来绝对比已发表的值小于0.8。但是，我们不能指出一个值，因为虚张声势的身体无法评估。我们还通过无线技术测量了气缸的基本压力，而没有任何支持干扰。结果表明，当阻力芯获得其最小值时，基本压力芯floffic级别获得了最大值。对测量压力波动的FFT分析也显示出定义的峰。此外，我们观察到轴向圆柱唤醒横截面上的涡旋中心以非轴向对称的方式以PIV测量即时移动。观察结果是在没有任何支持干扰的情况下进行的，因为我们使用了磁悬架和平衡系统。这项研究的流动将对支持系统非常敏感，并且使用磁悬浮液进行的测量是这种测试的理想方式。较少的

项目成果

気流に平行に磁力支持された円柱の抵抗係数

与气流平行的磁力支撑气缸的阻力系数

• 发表时间: 2004
• 期刊: 日本風工学会論文集 第29巻第4号
• 作者: 澤田秀夫;樋口 博;国益徹也;須田信一
• 通讯作者: 須田信一

Drag coefficients of cylinders magnetically supported in axial flow

轴流磁力支撑圆柱体的阻力系数

• 发表时间: 2004
• 期刊: J.of Wind Engineering, JAWE Vol.29, No.4
• 作者: H.Sawada;H.Higuchi;T.Kunimasu;S.Shinichi
• 通讯作者: S.Shinichi