施工隧道负离子除尘效率的主要影响因素

为研究施工隧道内粉尘颗粒粒径、颗粒浓度、通风风速和负离子系统工作电压、纵向安装位置对负离子系统粉尘降除效率的影响，依据调研和实测选取隧道计算参数，建立隧道及负离子系统三维模型，采用RNG k-ε双方程湍流模型，并通过动量方程附加电场力源项的方法求解电流场，利用拉格朗日法求解粉尘颗粒的运动轨迹，用SIMPLE算法对颗粒运动与电场流场进行离散相和流体相相间耦合的数值模拟计算，并将模拟结果和隧道现场抽样试验结果对比分析. 研究结果表明:隧道粉尘粒径越大，浓度越大，风速越低，负离子系统工作电压越高，系统纵向安装位置越偏于上风口，负离子系统除尘效率越高；两组现场抽样试验与对应数值模拟所得的除尘效率分别为41.2%、56.7%和38.2%、51.1%，误差分别为15.5%和12.9%. 考虑施工隧道大空间复杂环境的影响，通过数值模拟的方法来研究负离子系统除尘效率及其与主要影响因素的关系是可行的. 

Main Influencing Factors of Dust Removal Efficiency by Negative Ionization in Tunnel Construction

In order to study the influence of dust particle size, particle concentration, ventilation velocity, the working voltage of a negative ion system and its longitudinal installation position on the dust removal efficiency of the negative ion system in tunnel construction, a three-dimensional model of tunnel and negative ion system is established and the tunnel calculation parameters are selected according to investigation and measurement for numerical simulations. The RNG k-ε dual equation turbulence model is used to solve the current field by the momentum equation with electric field force source term. The trajectory of dust particles is solved by Lagrange method. The SIMPLE (semi-implicit method for pressure linked equations) algorithm is used to simulate the coupling between discrete and fluid phases of electric field, flow field and particle motion. In addition, field tests in the tunnel were carried out to verify the accuracy of the simulation results. The results show that the dust removal efficiency of the negative ion system improves with larger dust particle size, greater dust concentration, lower wind speed of the tunnel, higher working voltage of the negative ion system, and closer installation position of the system to the tunnel working face. Dust removal efficiencies of two groups of field sampling tests were 41.2% and 56.7% while the counterparts of numerical simulations were 38.2% and 51.1%, hence deviations being 15.5% and 12.9%, respectively. Therefore, considering the influence of large space and complex environment of tunnel under construction, it is feasible to study the dust removal efficiency of negative ion system and its relationship with main influencing factors by numerical simulation.