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Predictions of Brownout Dust Clouds Compared to Photogrammetry Measurements

机译：与摄影测量法比较的节电尘埃云预测

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摘要

Results from a Lagrangian-Lagrangian-based brownout simulation were compared to photogrammetric measurements of the evolving dust clouds generated by a helicopter during low altitude taxi-pass and approach-to-touchdown maneuvers. An inviscid-viscous method was used to represent the carrier phase from a combination of the rotor flow field (modeled as an inviscid flow using a free-vortex wake) and a semiempirical boundary layer flow model at the ground. The mobilization and initial uplift of dust particles were represented using semiempirical models for the effects of shear, unsteady pressures, and bombardment mechanisms, the subsequent particle motion being solved for by using a subset of the Basset-Boussinesq-Oseen equations. Although not all the measurements required for validation were available, the results showed good agreement to the measured evolution of the dust clouds. The results showed a significant sensitivity to the weight of the helicopter, as well as the initial flight path that it followed toward the ground. Small ambient winds were also found to affect both the initial development and the subsequent movement of the dust clouds. A particle quantity analysis showed that the majority of the smaller sized particles were uplifted by direct entrainment and bombardment ejection mechanisms, which when acting together rapidly increased the net quantity of suspended dust.
机译：将基于Lagrangian-Lagrangian的电力不足模拟的结果与直升机在低空滑行通过和着陆着陆操作期间产生的不断发展的尘埃云的摄影测量结果进行了比较。使用无粘性方法从转子流场（使用自由涡流尾流建模为无粘性流）和地面的半经验边界层流模型的组合表示载波相位。尘埃颗粒的动员和初始隆起用半经验模型表示，用于剪切，非恒定压力和轰击机制的影响，随后的颗粒运动通过使用Basset-Boussinesq-Oseen方程的子集解决。尽管并非验证所需的所有测量值都可用，但结果表明与尘埃云的测量演变有很好的一致性。结果表明，对直升机的重量以及其跟随地面的初始飞行路径具有明显的敏感性。还发现较小的环境风会影响尘埃云的初始发育和随后的运动。颗粒数量分析表明，大多数较小尺寸的颗粒是通过直接夹带和轰击喷射机制提升的，这两种机制一起作用会迅速增加悬浮粉尘的净含量。

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  • 来源
    《Journal of the American Helicopter Society》 |2013年第2期|022001.1-022001.18|共18页
  • 作者

    Monica Syal; J. Gordon Leishman;

  • 作者单位

    Department of Aerospace Engineering, University of Maryland, College Park, MD;

    Department of Aerospace Engineering, University of Maryland, College Park, MD;

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