The movement of people and other objects indoors may affect airflow patterns and velocities near local exhaust ventilation hoods, and consequently has influence on the hoods’ ability to remove locally emitted contaminants and on ventilation energy requirements. In this study, such disturbance effects have been studied experimentally and numerically, with the movements consisting of a human-sized plate, cylinder and detailed manikin, respectively, making back-and-forth movements near an exhaust hood. In the experimental part of the study, a 3-D sonic anemometer was used to measure air velocity in front of the hood opening. The numerical simulations used dynamic mesh to handle object movements. The numerical results were validated against the experimental ones and yielded supplementary results on the air flow field. The results show that the turbulence produced by the objects movements included marked air velocity peaks – both assisting and impeding the suction flow – in the near field of the exhaust hood. The generated turbulence, and particularly those peaks, proved substantially larger in the case of plate movement than with cylinder and manikin movement. Overall the results indicate that a moving cylinder represents human movement better than a moving plate, and thus that it’s better to use a cylinder in some test standards that now stipulate a plate as moving object. A Percentage of Negative Velocity (PNV) parameter was introduced for assessing the capture efficiency of the local exhaust system. The PNV represents the percentage of time that the air flow is directed away from the exhaust hood in an imagined point of contaminant release. The study includes test cases where the PNV values were significantly above zero, suggesting a strong effect on the capture efficiency of the exhaust hood. Human induced turbulence that cause such reverse air flows and overall impedes hood suction may be counteracted by enhanced exhaust flow rate, but then at higher energy consumption.

室内人员和其他物体的移动可能会影响局部排气通风罩附近的气流模式和速度，从而影响通风罩去除局部排放污染物的能力和通风能量需求。在这项研究中，已经通过实验和数值研究了这种干扰效应，运动分别由人体大小的板、圆柱体和详细的​​人体模型组成，在排气罩附近进行前后运动。在研究的实验部分，使用 3-D 声波风速计测量引擎盖开口前的空气速度。数值模拟使用动态网格来处理对象运动。数值结果与实验结果进行了验证，并在气流场上产生了补充结果。结果表明，物体运动产生的湍流包括排气罩近场中明显的空气速度峰值 - 有助于和阻碍吸入流。所产生的湍流，尤其是那些峰值，证明在板运动的情况下比在圆柱体和人体模型运动的情况下要大得多。总的来说，结果表明移动的圆柱体比移动的板更能代表人体运动，因此在一些现在规定板为移动物体的测试标准中最好使用圆柱体。引入了负速度百分比 (PNV) 参数来评估局部排气系统的捕获效率。PNV 表示空气流在想象的污染物释放点离开排气罩的时间百分比。该研究包括 PNV 值显着高于零的测试案例，这表明对排气罩的捕获效率有很大影响。人为引起的湍流会导致这种反向空气流动并总体上阻碍发动机罩抽吸，这可能会被提高的排气流速所抵消，但随后会消耗更高的能量。