Unsteady engulfment flow regime in T-jets reactor

doi:10.11949/j.issn.0438-1157.20180464

Abstract

Abstract:

Flow regimes in the T-jets reactor were studied by planar laser induced fluorescence (PLIF) technique and large-eddy simulation (LES). It was found that four different flow regimes, the separated flow (Re<120), steady engulfment flow (120 ≤ Re<190), unsteady engulfment flow (190 ≤ Re ≤ 300) and unsteady symmetric flow (Re>300) displayed in turns with the increase of Reynolds number. In particular, the characteristics of unsteady engulfment regime were investigated by LES. The results showed that eddies periodically merged in the impingement plan and the subsequent merged eddies passed through the chamber which caused self-sustained oscillation in the reactor. The pressure, velocity and vorticity in the impact zone also varied periodically, and the periods were consistent with that of eddy merging in unsteady engulfment regime. This oscillation of eddy merging and propagation is caused by the periodic variation of velocity and pressure in the impingement plane.

Key words: T-jets reactor, engulfment flow, oscillation, PLIF, large-eddy simulation

摘要：

运用激光诱导荧光（PLIF）技术和大涡模拟方法对T型反应器内的流动特性进行了研究。发现随着Reynolds数（Re）的增大，T型反应器中依次出现分离流（Re<120）、稳定吞噬流（120≤Re<190）、非稳态吞噬流（190≤Re≤300）、非稳态对称流（Re>300）四种流动模式。通过大涡模拟重点考察了非稳态吞噬流的振荡特性。结果表明，在非稳态吞噬流型下，T型反应器内撞击面上会周期性地出现旋涡合并现象，合并的涡向下传递，产生自持振荡。此时撞击区的压力、速度和涡量也发生周期性变化，且变化周期与旋涡合并周期相同，这种振荡是由速度和压力的周期性转换引起的。

关键词: T型反应器, 吞噬流, 振荡, PLIF, 大涡模拟

CLC Number:

TQ021.1

XU Xinlei, YAN Jiawei, ZHANG Wei, LI Weifeng, ZHANG Jingwei, LIU Haifeng, WANG Fuchen. Unsteady engulfment flow regime in T-jets reactor[J]. CIESC Journal, 2018, 69(12): 5073-5080.

许鑫磊, 严嘉玮, 张巍, 李伟锋, 张经纬, 刘海峰, 王辅臣. T型反应器内非稳态吞噬流机理[J]. 化工学报, 2018, 69(12): 5073-5080.

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