非等温平行流下吹吸式通风系统流场的数值模拟

Numerical Simulation of Flow Field in Blow-Suction Ventilation System Under the Non-Isothermal Parallel Flow

为探究非等温平行流下吹吸式通风系统的流场与污染物扩散规律,采用CFD的方法模拟典型三维一吹一吸两侧中心对称排布的吹吸式通风系统。对比模拟结果与实验数据,得知两者的变化趋势基本吻合。研究结果表明,当流场中送风速度一定、射流与环境空气存在温差时,随着温差增大,阿基米德数增大,轴心速度快速递减;轴心温度沿着吹吸流场方向下降;涡流中心先增高后降低。污染物扩散方面,当送风温度接近环境温度时,系统吸收污染物的能力最好。当射流与环境温差一定时,流场中送风速度增大,阿基米德数减小,轴心温度先增大后减小,流场的涡流中心向上偏移程度减小。可见,增加送风速度有利于系统的污染物吸收,减少污染物逃逸。

In view of an inquiry into the flow field and pollutant diffusion law of the blow-suction ventilation system under the non-isothermal parallel flow,CFD method is used for a simulation of the typical three-dimensional blow-suction ventilation system with a symmetrical arrangement on both sides.A comparison between the simulation results and the experimental data reveals that the change trend is basically consistent.The results show that when the air supply velocity in the flow field remains constant,with a temperature difference between the jet and the ambient air,the Archimedes number increases while the axial velocity decreases rapidly with an increase of the temperature difference.The axis temperature decreases along the direction of the blowing and suction flow field,whereas the vortex center shows an initially increasing and a subsequently decreasing trend.In terms of pollutant diffusion,with the air supply temperature close to the ambient temperature,the system is characterized with the strongest ability for the pollutant absorption.When there is a constant temperature difference between the jet and the environment,the air supply speed in the flow field increases,while the Archimedes number decreases;the axis temperature increases first and then decreases,while the upward shift of the vortex center in the flow field decreases.In terms of pollutant diffusion,an increase in the air supply speed is conducive to pollutant absorption in the system,thus reducing the escape of pollutants.