Accurate predictions of decaying swirling flow behavior in the multi-lobed swirl generator (MLSG) are essential for certain engineering applications. In this study, decaying swirling flow characteristics in an MLSG are examined using the Computational Fluid Dynamics (CFD) technique with a Reynolds stress turbulence model (RSM). The effects of different lobe numbers (n) and pitch length ratios (P/D) on swirl intensity, pressure drop, friction factor coefficient, and decay rate are observed with Reynolds number from 50,000 to 125,000. Combined with the pressure loss, the efficiency of swirl induction is evaluated by introducing a swirl effectiveness (SE) evaluation criterion. The initial swirl intensity is shown to first increases and then decreases as lobe number increases. The maximum value is obtained at lobe number n = 4. The pitch length ratios P/D corresponding to the optimal SE value obtained from different lobe also differ. The optimal SE value is achieved at n = 4 and P/D = 8. The friction factor ratio f _s/f _p decreases as pitch length ratio increases, but the decreasing trend decelerates over time. Correlations based on the numerical predictions of friction factor ratio f _s/f _p and decay rate β are presented accordingly.

对多瓣旋流发生器（MLSG）的衰减旋流特性的准确预测对于某些工程应用至关重要。在这项研究中，使用雷诺应力湍流模型（RSM）的计算流体动力学（CFD）技术检查了MLSG中的衰减旋流特性。不同瓣数（n）和音高长度比（P / D的影响）。）的涡旋强度，压降，摩擦因数系数和衰减率在雷诺数为50,000至125,000时观察到。结合压力损失，通过引入旋流效率（SE）评估标准来评估旋流诱导的效率。初始涡流强度显示为先增大，然后随着波瓣数增加而减小。在波瓣数n  = 4处获得最大值。对应于从不同波瓣获得的最佳SE值的音高长度比P / D也不同。最佳SE值在n  = 4且P / D  = 8时达到。摩擦系数比f _s / f _p随着节距长度比的增加而减小，但是减小的趋势随着时间的过去而减速。相应地提出了基于摩擦系数比f _s / f _p和衰减率β的数值预测的相关性。