Numerical Simulation and Experimental Validation of the Three-Dimensional Flow Field and Relative Analyte Concentration Distribution in an Atmospheric Pressure Ion Source
Numerical Simulation and Experimental Validation of the Three-Dimensional Flow Field and Relative Analyte Concentration Distribution in an Atmospheric Pressure Ion Source
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DOI：
10.1007/s13361-011-0211-z
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发表时间：
2011-11-01
影响因子：
3.2
通讯作者：
Benter, Thorsten
中科院分区：
文献类型：
--
作者：
Poehler, Thorsten;Kunte, Robert;Benter, Thorsten
本文对多用途离子源(MPIs)内气体流动的稳态数值模拟进行了验证和分析。实验结果是用粒子图像测速仪(PIV)在非定标的MPIS上获得的。给出了两种干气体积流量下的二维时均速度分布和湍动能分布。验证模拟的数值结果与实验数据吻合较好。所有重要的流动特征都在实验的精度范围内得到了正确的预测。由于技术原因，实验是在室温下进行的。因此，还给出了MPIs两个工作点的电离条件的数值模拟。结果表明，干气体积流量对APLI源内的整体流型影响最大，而雾化气体流量(较大)影响较小。除了雷诺平均Navier-Stokes方程的近似解外，还求解了相对分析物浓度的输运方程。结果提供了有关污染源内的三维分析物分布的信息。很明显，对于进入MS离子转移毛细管的离子传输，电磁力至少与流体动力力一样重要。然而，只有流体动力学才能确定分析气体的三维分布。因此，靠近喷雾屏蔽层的局部流动现象对电离效率有很大影响。
In this study, the validation and analysis of steady state numerical simulations of the gas flows within a multi-purpose ion source (MPIS) are presented. The experimental results were obtained with particle image velocimetry (PIV) measurements in a non-scaled MPIS. Two-dimensional time-averaged velocity and turbulent kinetic energy distributions are presented for two dry gas volume flow rates. The numerical results of the validation simulations are in very good agreement with the experimental data. All significant flow features have been correctly predicted within the accuracy of the experiments. For technical reasons, the experiments were conducted at room temperature. Thus, numerical simulations of ionization conditions at two operating points of the MPIS are also presented. It is clearly shown that the dry gas volume flow rate has the most significant impact on the overall flow pattern within the APLI source; far less critical is the (larger) nebulization gas flow. In addition to the approximate solution of Reynolds-Averaged Navier-Stokes equations, a transport equation for the relative analyte concentration has been solved. The results yield information on the three-dimensional analyte distribution within the source. It becomes evident that for ion transport into the MS ion transfer capillary, electromagnetic forces are at least as important as fluid dynamic forces. However, only the fluid dynamics determines the three-dimensional distribution of analyte gas. Thus, local flow phenomena in close proximity to the spray shield are strongly impacting on the ionization efficiency.