车内甲醛浓度及其动态分布数值仿真分析

Numerical Analysis of Formaldehyde Mass Concentration and Its Dynamic Distribution in Automobiles

针对高污染、高危害的甲醛在乘用车内通风条件下的动态分布特征及规律的研究相对缺乏,应用计算流体动力学(Computational Fluid Dynamics,CFD)理论和Fluent软件建立车内甲醛浓度及其分布数值仿真模型,并验证其可靠性.以温度、通风速率和通风模式因素为变量,基于车内空气流场分析,率先研究乘用车内甲醛质量浓度分布及其动态变化规律,首次系统地探讨温度、通风速率、通风模式对驾驶员和乘员呼吸关键点位甲醛质量浓度分布及其变化规律.结果表明,温度对车内甲醛质量浓度影响显著;0.5 m/s和4.0 m/s通风速率下甲醛浓度由于涡旋流场而分别呈现“双曲线”和“驼峰”型分布特征.关键点位驾驶员呼吸位置的甲醛浓度随通风速率增加而增加,当通风速率≤1.6 m/s时,增长速率为16.5%;当通风速率>1.6 m/s后,增长速率为3.6%;整车检测点的甲醛浓度随通风速率增加呈线性增长,增长率约为10.8%.车内后排空间甲醛浓度高于前排空间.

Considering the lack of investigation on the dynamic distribution characteristics and the law of formaldehyde under the ventilation condition in passenger cars,this paper applied Computational Fluid Dynamics(CFD)theory and Fluent software to establish a numerical simulation model for analyzing formaldehyde concentration and its distribution in vehicles,and verified its reliability.On this basis,the present work firstly studied the distribution and dynamic variation of formaldehyde mass concentration in passenger vehicles based on the analysis of the air flow field by taking temperature,ventilation rate and ventilation mode factors as variables.Especially,this study investigated the influence of temperature,ventilation rate and ventilation mode on formaldehyde mass concentration at the breathing positions of drivers and passengers,as well as some typical sampling lines in vehicles.The results indicated that the temperature has a significant effect on the formaldehyde concentration in a car.It was also found that formaldehyde concentration at 0.5 m/s and 4.0 m/s ventilation rates presented different distribution characteristics of“hyperbola”and“hump”,respectively,due to vortex flow field.Formaldehyde mass concentration at the driver’s breathing position increased with the increase of ventilation rate.When the ventilation rate is not larger than1.6 m/s,the growth rate is 16.5%;When the ventilation rate is larger than 1.6 m/s,the growth rate decreases to 3.6%.The formaldehyde concentration at the vehicle detection point showed a linear growth trend with the air velocity rate at growth rate of 10.8%.The formaldehyde concentration in the rear row is higher than that in the front row in a car.