Drag-Reducing Techniques for Axi-Symmetric Bluff Bodies
Drag-Reducing Techniques for Axi-Symmetric Bluff Bodies
复制标题
轴对称钝体减阻技术
DOI：
10.1007/978-1-4684-8434-2_7
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
W. A. Mair
中科院分区：
文献类型：
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作者：
W. A. Mair
在二维钝体减阻装置上进行的大量实验已被用作指导轴对称体研究的有前景的路线。对于后一种情况，回顾了分流板、圆柱形延伸件、底部排气和通风腔的实验。在这些装置中，底排是唯一能够有效减少阻力的装置。不幸的是，底排不能有效地应用于道路车辆。典型车辆的通风系统提供的空气流量太小，无法产生任何显着效果。如果提供提供更大气流的特殊空气供应，则进气动量阻力将足以抵消由于底部排气而造成的任何阻力减少。对于钝基轴对称车身，船尾尾部在减少零偏航阻力方面比任何其他已尝试过的装置更有效。此外，实验表明，当船尾体的偏航角从零开始增加时，轴向力会略有下降，直至偏航角约为 10 或 15 度，尽管在较大的偏航角下轴向力会变得更大。解释了船尾尾体的作用模式，并讨论了导致良好设计的一些因素。简要考虑了将边界层控制与船尾尾部结合使用的可能性。
The numerous experiments that have been made on drag-reducing devices fortwo-dimensionalbluff bodies have been used as a guide to indicate promising lines of investigation for axi-symmetric bodies. For the latter case, experiments on splitter plates, cylindrical extensions, base bleed and ventilated cavities are reviewed. Of these devices, base bleed is the only one that gives any useful reduction of drag. Unfortunately base bleed cannot be effectively applied to road vehicles. The air flow rate available on a typical vehicle from its ventilation system is too small to give any significant effect. If a special air supply giving a larger air flow were to be provided, the intake momentum drag would be more than enough to counteract any drag reduction due to base bleed.For a blunt-based axi-symmetric body, a boat-tailed afterbody is much more effective in reducing zero-yaw drag than any other device that has been tried. Furthermore, experiments have shown that as the yaw angle of a boat-tailed body is increased from zero, the axial force can decrease slightly up to a yaw angle of about 10 or 15 degrees, although at larger yaw angles it becomes much greater.The mode of action of a boat-tailed afterbody is explained, and some of the factors leading to a good design are discussed. The possibility of using boundary-layer control in conjunction with a boat-tailed afterbody is considered briefly.