Simulation of Fluid Flow and Collection Efficiency for an SEA Multi-element Probe
Simulation of Fluid Flow and Collection Efficiency for an SEA Multi-element Probe
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SEA 多元件探头的流体流动和收集效率模拟
DOI：
10.2514/6.2014-2752
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
C. Bidwell
中科院分区：
文献类型：
--
作者：
D. Rigby;P. Struk;C. Bidwell
介绍了科学工程协会 (SEA) 多元件探针的流体流动和收集效率的数值模拟。使用 Glenn-HT Navier-Stokes 求解器进行流场模拟。产生三维非稳态结果，然后对传热和收集效率结果进行时间平均。研究了三种网格密度以评估网格依赖性。模拟完成的自由流速度范围为 85-135 米每秒，自由流总压力为 44.8 和 93.1 千帕（6.5 和 13.5 磅每平方英寸绝对压力）。此外，还通过在其中一种流动条件下包含 5 度的直线偏差来研究迎角和偏航的影响。除一种情况外，所有情况都模拟了孤立的探头（即在没有任何支撑杆的非常大的域中）。其中包括一个案例，代表安装在有限尺寸风洞内的支撑杆上的探头。使用 LEWICE3D 代码生成四种球形颗粒尺寸（直径为 100、50、20 和 5 微米）的收集效率。据观察，在所有情况下，当流体进入探头护罩时，速度都会降低约 20%。护罩内速度的降低并不表示探头测量精度存在任何误差。给出的传热结果与圆形横截面加热元件的相关性非常吻合。收集效率结果表明收集效率随着颗粒尺寸的减小而降低。预计颗粒尺寸会减小，但是，结果往往低于先前针对孤立的二维元素生成的结果。对于较小的颗粒，与二维结果的偏差更为明显，这可能是由于保护罩内的流量减少所致。随着颗粒尺寸的增加，二维和三维结果之间的差异变得可以忽略不计。作为一个整体，对于 20 微米以上的颗粒，包括护罩效应在内的元件总收集效率已显示在 0.93 至 0.99 范围内。 3D 模型提高了对较小颗粒的估计收集效率，而先前估计的误差更为显着。
Numerical simulations of fluid flow and collection efficiency for a Science Engineering Associates (SEA) multi-element probe are presented. Simulation of the flow field was produced using the Glenn-HT Navier-Stokes solver. Three-dimensional unsteady results were produced and then time averaged for the heat transfer and collection efficiency results. Three grid densities were investigated to enable an assessment of grid dependence. Simulations were completed for free stream velocities ranging from 85-135 meters per second, and free stream total pressure of 44.8 and 93.1 kilopascals (6.5 and 13.5 pounds per square inch absolute). In addition, the effect of angle of attack and yaw were investigated by including 5 degree deviations from straight for one of the flow conditions. All but one of the cases simulated a probe in isolation (i.e. in a very large domain without any support strut). One case is included which represents a probe mounted on a support strut within a finite sized wind tunnel. Collection efficiencies were generated, using the LEWICE3D code, for four spherical particle sizes, 100, 50, 20, and 5 micron in diameter. It was observed that a reduction in velocity of about 20% occurred, for all cases, as the flow entered the shroud of the probe. The reduction in velocity within the shroud is not indicative of any error in the probe measurement accuracy. Heat transfer results are presented which agree quite well with a correlation for the circular cross section heated elements. Collection efficiency results indicate a reduction in collection efficiency as particle size is reduced. The reduction with particle size is expected, however, the results tended to be lower than the previous results generated for isolated two-dimensional elements. The deviation from the two-dimensional results is more pronounced for the smaller particles and is likely due to the reduced flow within the protective shroud. As particle size increases differences between the two-dimensional and three dimensional results become negligible. Taken as a group, the total collection efficiency of the elements including the effects of the shroud has been shown to be in the range of 0.93 to 0.99 for particles above 20 microns. The 3D model has improved the estimated collection efficiency for smaller particles where errors in previous estimates were more significant.