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首页> 外文会议>AHS International annual forum >Eulerian Simulation of the Fluid Dynamics of Helicopter Brownout
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Eulerian Simulation of the Fluid Dynamics of Helicopter Brownout

机译：直升机停电的流体动力学的欧拉模拟

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A computational model is presented that can be used to simulate the development of the dust cloud that can be entrained into the air when a helicopter is operated close to the ground in desert or dusty conditions. The physics of this problem, and the associated pathological condition known as 'brownout' where the pilot loses situational awareness as a result of his vision being occluded by dust suspended in the flow around the helicopter, is acknowledged to be very complex. The approach advocated here involves an approximation to the full dynamics of the coupled particulate-air system. Away from the ground, the model assumes that the suspended particles remain in near equilibrium under the action of aerodynamic forces. Close to the ground, this model is replaced by an algebraic sublayer model for the saltation and entrainment process. The origin of the model in the statistical mechanics of a distribution of particles governed by aerodynamic forces allows the validity of the method to be evaluated in context by comparing the physical properties of the suspended particulates to the local properties of the flow field surrounding the helicopter. The model applies in the Eulerian frame of reference of most conventional Computational Fluid Dynamics codes and has been coupled with Brown's Vorticity Transport Model. Verification of the predictions of the coupled model against experimental data for particulate entrainment and transport in the flow around a model rotor are encouraging. An application of the coupled model to analyzing the differences in the geometry and extent of the dust clouds that are produced by single main rotor and tandem-rotor configurations as they decelerate to land has shown that the location of the ground vortex and the size of any regions of recirculatory flow, should they exist, play a primary role in governing the extent of the dust cloud that is created by the helicopter.
机译：提出了一种计算模型，该模型可用于模拟在沙漠或尘土飞扬的条件下直升飞机在接近地面的情况下可以带入空中的尘埃云的发展。人们已经认识到，这个问题的物理性质以及与之相关的病理状况（称为“电力不足”），使飞行员由于视力被直升机周围气流中悬浮的灰尘所阻塞而失去了态势感知，因此被认为是非常复杂的。这里提倡的方法涉及到耦合颗粒空气系统的全部动力学的近似值。在远离地面的情况下，该模型假设悬浮颗粒在空气动力的作用下保持接近平衡。在地面附近，此模型被代入盐分和夹带过程的代数子层模型替代。模型的起源是由空气动力控制的颗粒分布的统计力学，通过比较悬浮颗粒的物理性质与直升机周围流场的局部性质，可以在上下文中评估该方法的有效性。该模型适用于大多数常规计算流体动力学代码的欧拉参考框架，并已与布朗的涡度传输模型耦合。令人鼓舞的是，根据实验数据对耦合模型的预测结果进行了验证，以验证模型转子周围气流中的颗粒夹带和传输。耦合模型在分析单个主旋翼和串联旋翼减速降落时产生的尘埃云的几何形状和范围差异中的应用表明，地面涡旋的位置和任何尘埃的大小再循环流区域（如果存在的话）在控制直升机产生的尘埃云的范围方面起主要作用。

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