方形截面纤维表面气溶胶粒子多机理过滤性能数值分析

采用数值方法求解绕方形截面纤维流场，考虑粒子布朗扩散、拦截效应和惯性碰撞捕集机理的联合作用，用布朗动力学方法研究方形截面纤维的过滤性能，考察了纤维迎风角(θ)、填充率(C)和过滤风速(u?)对捕集效率、质量因子及粒子沉积分布的影响。结果表明，小粒子的扩散捕集或大粒子的惯性捕集在方形纤维表面的粒子沉积行为均表现出显著的局部沉积特征，且与粒子捕集机理和迎风角有关。方形纤维质量因子的分析结果表明，在高填充率下，方形纤维的过滤压降虽高于圆截面纤维，但具有较高的捕集效率，综合过滤性能仍明显优于圆截面纤维，但在低填充率下，方形纤维综合过滤性能劣于圆截面纤维。

Numerical analysis of multi-mechanism filtration performance by square fibers for aerosol particles

The filtration performance of square fiber was studied by using a Brownian dynamics simulation technique, which allowed for simultaneous consideration of all the important mechanisms of particle capture including Brownian diffusion, interception and inertial impaction. The flow around square fiber used for evaluating the particle trajectories was solved numerically. The effects of orientation angle θ, the fiber volume fraction C and the filtration velocity u∞ on capture efficiency, quality factor as well as the distributions of deposited particle were discussed and analyzed. The results showed that the distributions of deposited particle over a single square fiber were characterized by localized regional deposition for both diffusional deposition of small particles and inertial capture of large particles, and were significantly influenced by capture mechanisms and orientation angles. According to the calculated results for the filtration pressure drop and capture efficiency, the quality factor of square fibers with various orientation angles were then evaluated, and the results indicated that in the case of high fiber volume fraction, the square fiber showed higher comprehensive filtration performance than the cylindrical fiber even though its filtration pressure drop was much higher. However, in the case of low fiber volume fraction, the square fiber showed lower comprehensive filtration performance than the cylindrical fiber.