基于壁面射流的虚拟冲击式采样分离器的优化

Optimization of virtual impact sampling separator based on wall jets

为了提高现有虚拟冲击技术下的呼吸性粉尘采样分离器的分离标准差,采用壁面射流中的附壁效应,结合模型角度改变对颗粒捕获效率的影响,在凸型内壁的分离腔基础上,研究加速喷嘴尾部的角度、外壁面顶点的角度和喷嘴至收集腔的距离3个方面因素对于模型分离效率的影响。采用有限元软件ANSYS Fluent的气固两相流数值仿真,仿真模拟分离器的内部流场,在仿真过程中对颗粒进行捕捉跟踪,将计算出的分离效率与BMRC曲线的标准进行比较。结果表明:与凸型内壁结构的采样分离器模型相比,改进后的呼吸性粉尘采样分离器在粒径较小处的分离效率方程更贴近BMRC曲线,分离偏差均小于1.6%,分离标准差达到了δ_(2)=2.31%,在参考模型的分离标准差上提高了12.83%。

In order to improve the separation standard deviation of the respiratory dust sampling separator under the existing virtual impact technology, the wall effect in the wall jet was adopted, and the influence of the changed model angle on the particle capture efficiency was combined. On the basis of the separation cavity of the convex inner wall, the angle of the accelerated nozzle tail, the angle of the vertex of the outer wall, and the distance from nozzle to collect cavity were studied on the effect of model separation.Through the gas-solid two-phase flow mode of the finite element software ANSYS Fluent, the flow field inside the separator was simulated. The particles were captured and tracked during the simulation, and the resulting separation efficiency was compared to the standard of the BMRC curve. The results show that compared with the separator model with convex inner wall structure, the separation efficiency of the improved respiratory dust sampling separator at the smaller particle size is closed to the BMRC curve, the separation deviation is limited to less than 1.6%, and the separation standard deviation is proved to be 12.83% higher than that of the reference model, reaching δ_(2)=2.31%.