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首页> 外文会议>41st AIAA fluid dynamics conference and exhibit 2011 >Study of Factors Driving Pitch, Roll and Yaw Coupling in Bluff Body Aerodynamics
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Study of Factors Driving Pitch, Roll and Yaw Coupling in Bluff Body Aerodynamics

机译：钝体空气动力学中驱动俯仰，横摇和横摆耦合的因素研究

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摘要

Helicopter sling loads exhibit departures from stable behavior at certain speeds posing certain safety concerns. Rolling due to pendulum motion about the sling attachment point may couple with yaw and pitch oscillations, amplifying the motion to dangerous levels at certain speeds. This is a case of coupling between the aerodynamic forces and the dynamics of the tethering system, and can affect the handling qualities of the vehicle as well. In this work the factors driving the pitch, roll and yaw coupling in bluff body aerodynamics are studied. The sensitivity of the side force and yawing moment to yaw angle is studied in a low speed wind tunnel, in steady-state load measurements simulating the effect of velocity induced by quasi-steady pendulum-type roll motion. While the side force and yawing moment appear to be generally stable to induced yaw, at some speeds there is a reversal of the stability derivative, partially explaining observed behavior in tethered tests. The time-averaged side force and yawing moment behavior with yaw angle generally agree with predictions made using unstructured-grid Navier-Stokes computations. While the time-averaged loads at small yaw angles are small, there are substantial unsteady oscillations of the loads about these values. A hot-film constant temperature anemometer probe is used to measure spectra of velocity fluctuations near the edge of the model and in the wake downstream. Spectral peaks of integrated loads observed in 2-D computations occur in the same frequency band as those seen in the measured velocity spectra.
机译：直升机吊索载荷在一定速度下表现出偏离稳定状态的特性，从而带来了某些安全隐患。由于摆线运动围绕吊索连接点而产生的滚动可能会伴随偏航和俯仰振荡，从而在一定速度下将运动放大到危险水平。这是空气动力与系留系统动力学之间耦合的情况，并且也会影响车辆的操纵质量。在这项工作中，研究了钝体空气动力学中驱动俯仰，侧倾和偏航耦合的因素。在低速风洞中研究了侧向力和偏航力矩对偏航角的敏感性，在稳态载荷测量中模拟了准稳态摆式侧倾运动对速度的影响。虽然侧向力和偏航力矩对于诱导的偏航似乎总体上是稳定的，但在某些速度下，稳定性导数发生了逆转，部分解释了系留测试中观察到的行为。具有偏航角的时均侧向力和偏航力矩特性通常与使用非结构化网格Navier-Stokes计算得出的预测一致。虽然在小偏航角下的时间平均负载很小，但是负载在这些值附近存在相当大的不稳定波动。热膜恒温风速计探头用于测量模型边缘附近和下游尾流处的速度波动谱。在二维计算中观察到的积分载荷的谱峰出现在与测得的速度谱相同的频带中。

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