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首页> 外文期刊>Building and Environment >Turbulent characteristics in the near fields of gasper jet flows in an aircraft cabin environment: Intermittently energetic coherent structures
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Turbulent characteristics in the near fields of gasper jet flows in an aircraft cabin environment: Intermittently energetic coherent structures

机译：机舱环境中气喷流近场的湍流特征：间歇性高能相干结构

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In an aircraft cabin environment, a gasper nozzle is a type of air conditioning and part of the air recirculation system, and its near fields are dominated by intermittently energetic coherent structures (IECSs). Based on the percentage of dissatisfied (PD) model, the turbulent intensity and the intermittent frequency of IECSs are investigated in this study as main factors of draught sensation. The gasper jet flow fields at several Reynolds numbers (Re = 2000 similar to 17,047) are determined using a hot-wire anemometer, and a round-pipe jet flow is used for comparison. The mean velocity and streamwise gradient exhibit self-similarity after the reattachment point. Pre-multiplied energy spectra provide the energetic length scales of the intermittent coherent structures. Then, continuous wavelet transform is employed to detect the IECSs. The average waveform indicates that along the axis direction, the IECSs exhibit unstable coherence, symmetric and oscillating waveforms. All of these signatures are independent of the nozzle geometry and display an earlier emergence with an increase in Re. Furthermore, the mean turbulent intensity and waiting time of the IECSs are explored. Compared with the round-pipe jet, the IECSs in the gasper jet flows have a lower mean turbulent intensity. The analysis of the probability density function indicates that the waiting time between the successive IECSs is almost twice that of the energetic length scale, and the dimensionless result presents that the intermittent frequency has the self-similar distribution for all the cases in this study. (C) 2017 Elsevier Ltd. All rights reserved.
机译：在飞机机舱环境中，加气嘴是一种空调，是空气再循环系统的一部分，其近场由间歇性高能相干结构（IECS）支配。基于不满意（PD）模型的百分比，研究IECS的湍流强度和间歇频率是影响吃水的主要因素。使用热线风速计确定几个雷诺数（Re = 2000，类似于17,047）下的气喷流场，并使用圆管喷流进行比较。在重新连接点之后，平均速度和流向梯度表现出自相似性。预乘能谱提供了间歇相干结构的能量长度尺度。然后，采用连续小波变换检测IECS。平均波形表明，IECS沿轴方向显示出不稳定的相干，对称和振荡波形。所有这些特征均与喷嘴的几何形状无关，并且随着Re的增加而显示出较早的出现。此外，还研究了IECS的平均湍流强度和等待时间。与圆管射流相比，加气射流中的IECS具有较低的平均湍流强度。对概率密度函数的分析表明，连续的IECS之间的等待时间几乎是能量长度尺度的等待时间的两倍，无量纲结果表明，在本研究中，所有情况下的间歇频率都具有自相似分布。 （C）2017 Elsevier Ltd.保留所有权利。

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