Effects of Scalloping on the Mixing Mechanisms of Forced Mixers With Highly Swirling Core Flow
Effects of Scalloping on the Mixing Mechanisms of Forced Mixers With Highly Swirling Core Flow
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DOI：
10.1115/1.4024043
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发表时间：
2012-06
影响因子：
1.5
通讯作者：
A. Wright;Zhijun Lei;A. Mahallati;Mark Cunningham;J. Militzer
中科院分区：
文献类型：
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作者：
A. Wright;Zhijun Lei;A. Mahallati;Mark Cunningham;J. Militzer
本文详细地研究了扇形对12叶涡轮风扇混合器混合机理的影响。通过消除约70%的瓣侧壁面积来实现扇形化。在共环风洞中对混合器下游进行了测量，并使用非结构雷诺平均Navier-Stokes（RANS）求解器Numeca FINE/Hexa和k-ω SST模型进行了模拟。在核心流中，旋流角从0 °变化到30 °。在高旋流角下，在叶片吸力面穿透区域形成三维分离泡，并导致在叶片谷处产生涡流。山谷漩涡迅速向下游消散。混合器叶片去除了大部分涡流，但扇形叶片去除了扇形凹口区域中的较少涡流。扇形混合器下游的残余涡流与涡流相互作用，与无扇形混合器相比，改善了混合速率。核心流涡流高达10度提供了改善的混合率和减少压力和推力损失的两个混合器。当中心流涡流增加到10度以上时，混合率继续提高，但与零涡流情况相比，压力和推力损失下降。在高旋流条件下，叶片扇形比无扇形混合器更好地混合并改善了压力损失，但以减少推力为代价。
This paper presents a detailed experimental and computational investigation of the effects of scalloping on the mixing mechanisms of a scaled 12-lobe turbofan mixer. Scalloping was achieved by eliminating approximately 70% of the lobe sidewall area. Measurements were made downstream of the mixer in a co-annular wind tunnel, and the simulations were carried out using an unstructured Reynolds averaged Navier–Stokes (RANS) solver, Numeca FINE/Hexa, with k-ω SST model. In the core flow, the swirl angle was varied from 0 deg to 30 deg. At high swirl angles, a three-dimensional separation bubble was formed on the lobe's suction surface penetration region and resulted in the generation of a vortex at the lobe valley. The valley vortex quickly dissipated downstream. The mixer lobes removed most of the swirl, but scalloped lobes removed less swirl in the region of the scalloped notch. The residual swirl downstream of the scalloped mixer interacted with the vortices and improved mixing rates compared to the unscalloped mixer. Core flow swirl up to 10 deg provided improved mixing rates and reduced pressure and thrust losses for both mixers. As core flow swirl increased beyond 10 deg, the mixing rate continued to improve, but pressure and thrust losses declined compared to the zero swirl case. Lobe scalloping, in high swirl conditions, resulted in better mixing and improved pressure loss over the unscalloped mixer but at the expense of reduced thrust.