Helicopter tail shake phenomenon is still remained as a long dragged issue that adversely affected the overall performance, occupants’ comfortness and handling qualities of helicopter. This problem is more severe in modern helicopter as it needs to fly faster and with high manoeuvrability, causing rigorous interactional aerodynamic (I/A) related vibration problems. The objective of this present research is to improve basic understanding of the viscous unsteady flow phenomenon observed behind the helicopter tail part. A good understanding of this matter is necessary as a typical aspect of tail shake that it has unsteady random character, indicating that the wake induced excitation is in also unsteady of nature. For this, a wind tunnel test had been conducted with a rigid 14% model of generic Eurocopter 350Z helicopter in the Universiti Teknologi Malaysia – Low Speed Tunnel (UTM-LST) with a test section size of 2m x 1.5m x 5.8m and 288 km/hr maximum test wind speed. The model, supplied by Eurocopter France, is equipped with a motor that can rotate the main rotor up to 900 rpm during wind-on condition. Therefore, the wake analysis can be done ‘with’ or ‘without’ main rotor rotation which undoubtly can give a more comprehensive understanding on the wake induced. As the induced wake, which consequently causing tail to shake, differs with pitch and yaw angle, the wind tunnel test was performed in a range of -10o to +10o of pitch and yaw angle, respectively. The selected test wind speed was 40 m/s, which corresponds to a Reynolds number of 3.7 x 106. To investigate the characteristics of the induced wake, a mapping process was done at 3 different planes behind the model with each plane consists of 4 measurement points. With this, it is hope the collected data could help on the wake analysis that contributes to helicopter tail shake phenomenon. DANTEC single hotwire, type 55P01, was used to determine local turbulence level and velocity at each respectively point throughout all the tests. However, only static results and analysis will be discussed in this paper.
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机译：直升机的尾部晃动现象仍然是一个长期拖累的问题，它严重影响了直升机的整体性能，乘员的舒适度和操纵质量。在现代直升机中，此问题更为严重，因为它需要更快地飞行并具有较高的机动性，从而导致与交互空气动力学（I / A）相关的严格振动问题。本研究的目的是提高对直升机尾部后面观察到的粘性非稳态流动现象的基本理解。有必要对此问题有一个很好的了解，因为它具有不稳定的随机特性，这是尾巴抖动的典型方面，这表明尾波诱发的激发也是不稳定的。为此，在马来西亚Teknologi大学“低速隧道（UTM-LST）”中使用刚性为14％的通用Eurocopter 350Z直升机模型进行了风洞测试，测试截面尺寸为2m x 1.5mx 5.8m，最高测试风速为288公里/小时。由法国欧洲直升机公司提供的模型配备有电动机，在上风条件下，该电动机可使主旋翼旋转至900 rpm。因此，尾流分析可以“有”或“没有”主转子旋转来完成，这无疑可以对引起的尾流有更全面的了解。由于导致尾部晃动的感应尾流随俯仰和偏航角的不同而不同，因此，风洞试验分别在俯仰和偏航角的-10o至+ 10o范围内进行。选定的测试风速为40 m / s，对应于3.7 x 106的雷诺数。为了研究诱发的尾波的特性，在模型后面的3个不同平面上进行了映射过程，每个平面包含4个测量值点。因此，希望收集到的数据有助于进行有助于直升机尾摇现象的尾迹分析。在所有测试中，均使用DANTEC 55P01型单根热线确定每个位置上的局部湍流水平和速度。但是，本文仅讨论静态结果和分析。
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