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The impact of atmospheric boundary layer, opening configuration and presence of animals on the ventilation of a cattle barn
Journal of Wind Engineering and Industrial Aerodynamics ( IF 4.8 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.jweia.2020.104185
Štěpán Nosek , Zuzana Kluková , Michala Jakubcová , Qianying Yi , David Janke , Peter Demeyer , Zbyněk Jaňour

Abstract Naturally ventilated livestock buildings (NVLB) represent one of the most significant sources of ammonia emissions. However, even the dispersion of passive gas in an NVLB is still not well understood. In this paper, we present a detailed investigation of passive pollutant dispersion in a model of a cattle barn using the wind tunnel experiment method. We simulated the pollution of the barn by a ground-level planar source. We used the time-resolved particle image velocimetry (TR-PIV) and the fast flame ionisation detector (FFID) to study the flow and dispersion processes at high spatial and temporal resolution. We employed the Proper Orthogonal Decomposition (POD) and Oscillating Patterns Decomposition (OPD) methods to detect the coherent structures of the flow. The results show that the type of atmospheric boundary layer (ABL) and sidewall opening height have a significant impact on the pollutant dispersion in the barn, while the presence of animals and doors openings are insignificant under conditions of winds perpendicular to the sidewall openings. We found that the dynamic coherent structures, developed by the Kelvin-Helmholtz instability, contribute to the pollutant transport in the barn. We demonstrate that in any of the studied cases the pollutant was not well mixed within the barn and that a significant underestimation (up to by a factor 3) of the barn ventilation might be obtained using, e.g. tracer gas method.

中文翻译:

大气边界层、开口结构和动物的存在对牛舍通风的影响

摘要 自然通风畜舍 (NVLB) 是氨排放的最重要来源之一。然而,即使是被动气体在 NVLB 中的分散情况仍然不是很清楚。在本文中,我们使用风洞实验方法对牛舍模型中的被动污染物扩散进行了详细研究。我们模拟了地面平面源对谷仓的污染。我们使用时间分辨粒子图像测速仪 (TR-PIV) 和快速火焰电离检测器 (FFID) 来研究高空间和时间分辨率下的流动和扩散过程。我们采用了适当的正交分解 (POD) 和振荡模式分解 (OPD) 方法来检测流的相干结构。结果表明,大气边界层(ABL)的类型和侧壁开口高度对畜舍内污染物扩散有显着影响,而在垂直于侧壁开口的风条件下,动物和门洞的存在不显着。我们发现由开尔文-亥姆霍兹不稳定性产生的动态相干结构有助于谷仓中的污染物传输。我们证明,在任何研究案例中,污染物在猪舍内都没有很好地混合,并且使用例如示踪气体方法可能会严重低估猪舍通风(高达 3 倍)。而在垂直于侧壁开口的风条件下,动物和门洞的存在是微不足道的。我们发现由 Kelvin-Helmholtz 不稳定性发展的动态相干结构有助于谷仓中的污染物传输。我们证明,在任何研究案例中,污染物在猪舍内都没有很好地混合,并且使用例如示踪气体方法可能会严重低估猪舍通风(高达 3 倍)。而在垂直于侧壁开口的风条件下,动物和门洞的存在是微不足道的。我们发现由开尔文-亥姆霍兹不稳定性产生的动态相干结构有助于谷仓中的污染物传输。我们证明,在任何研究案例中,污染物在猪舍内都没有很好地混合,并且使用例如示踪气体方法可能会严重低估猪舍通风(高达 3 倍)。
更新日期:2020-06-01
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