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Renormalisation of particle distributions in an initially-biased turbulent jet by swirl and radial injection
International Journal of Multiphase Flow ( IF 3.6 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.ijmultiphaseflow.2020.103509
Cristian H. Birzer , Peter A.M. Kalt , Timothy C.W. Lau , Graham  J. Nathan

Abstract The distribution of particles in a jet with an initial bias is assessed using planar nephelometry, which is a planar imaging technique using Mie-scattering. Initial biases in particle distributions can have large and significant effects, particularly in solid fuel combustion systems, where inhomogeneities will affect the local and global performance of a flame. In this study, a two-phase jet flow with a controlled initial bias is generated at a Stokes number, based on the large-eddy time-scale, of S k D = 0.39 , and various strategies are explored to correct this bias. The investigation examines the usefulness of injecting air at various momentum ratios and through various configurations upstream from the nozzle exit plane. The study examines the differential roles of swirl (tangential) and radial injection of air at various locations from the flow exit. Radial injection of momentum is found to be superior to injection of swirl, consistent with swirl being a magnifier of eccentricities of a flow. Radial injection upstream from the nozzle can achieve a re-homogenised flow to develop prior to the exit, at least for the present Stokes numbers, but can also lead to downstream biases in particle distribution for some conditions. Injecting momentum directly at the nozzle exit does not allow a symmetrical distribution to be achieved, but does have an observed influence on the emerging flow-field.

中文翻译:

通过旋流和径向注入对初始偏置湍流射流中的粒子分布进行重整化

摘要 使用平面比浊法评估具有初始偏置的射流中粒子的分布,这是一种使用米氏散射的平面成像技术。粒子分布的初始偏差会产生巨大而显着的影响,特别是在固体燃料燃烧系统中,其中不均匀性会影响火焰的局部和全局性能。在这项研究中,基于大涡时间尺度 S k D = 0.39 的斯托克斯数产生了具有受控初始偏差的两相射流,并探索了各种策略来纠正这种偏差。该研究检查了以各种动量比和通过喷嘴出口平面上游的各种配置喷射空气的有效性。该研究检查了从流动出口在不同位置喷射空气的旋流(切向)和径向喷射的不同作用。发现动量的径向注入优于旋流注入,这与旋流是流动偏心率的放大镜一致。喷嘴上游的径向喷射可以在出口之前实现重新均质化的流动,至少对于目前的斯托克斯数,但在某些情况下也可能导致下游的颗粒分布偏差。直接在喷嘴出口注入动量不允许实现对称分布,但确实对出现的流场有观察到的影响。喷嘴上游的径向喷射可以在出口之前实现重新均质化的流动,至少对于目前的斯托克斯数,但在某些情况下也可能导致下游的颗粒分布偏差。直接在喷嘴出口注入动量不允许实现对称分布,但确实对出现的流场有观察到的影响。喷嘴上游的径向喷射可以在出口之前实现重新均质化的流动,至少对于目前的斯托克斯数,但在某些情况下也可能导致下游的颗粒分布偏差。直接在喷嘴出口注入动量不允许实现对称分布,但确实对出现的流场有观察到的影响。
更新日期:2021-02-01
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