Investigation of flow characteristics in a rotor-stator cavity under crossflow using wall-modelled large-eddy simulation

IF 3.3 3区 工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY Journal of Zhejiang University-SCIENCE A Pub Date : 2023-05-22 DOI:10.1631/jzus.A2200565
Lei Xie, Qian Du, Guang Liu, Zengyan Lian, Yaguang Xie, Yifu Luo
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引用次数: 1

Abstract

Rotor-stator cavities are frequently encountered in engineering applications such as gas turbine engines. They are usually subject to an external hot mainstream crossflow which in general is highly swirled under the effect of the nozzle guide vanes. To avoid hot mainstream gas ingress, the cavity is usually purged by a stream of sealing flow. The interactions between the external crossflow, cavity flow, and sealing flow are complicated and involve all scales of turbulent unsteadiness and flow instability which are beyond the resolution of the Reynolds-average approach. To cope with such a complex issue, a wall-modeled large-eddy simulation (WMLES) approach is adopted in this study. In the simulation, a 20° sector model is used and subjected to a uniform pre-swirled external crossflow and a stream of radial sealing flow. It is triggered by a convergent Reynolds-averaged Navier-Stokes (RANS) result in which the shear stress transport (SST) turbulent model is used. In the WMLES simulation, the Smagoringsky sub-grid scale (SGS) model is applied. A scalar transportation equation is solved to simulate the blending and transportation process in the cavity. The overall flow field characteristics and deviation between RANS and WMLES results are discussed first. Both RANS and WMLES results show a Batchelor flow mode, while distinct deviation is also observed. Deviations in the small-radius region are caused by the insufficiency of the RANS approach in capturing the small-scale vortex structures in the boundary layer while deviations in the large-radius region are caused by the insufficiency of the RANS approach in predicting the external crossflow ingestion. The boundary layer vortex and external ingestion are then discussed in detail, highlighting the related flow instabilities. Finally, the large-flow structures induced by external flow ingress are analyzed using unsteady pressure oscillation signals.
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横流作用下动静腔内流动特性的壁型大涡模拟研究
在燃气涡轮发动机等工程应用中,经常遇到转子-定子空腔。它们通常受到外部热主流横流的影响,通常在喷嘴导叶的作用下高度旋转。为了避免热的主流气体进入,通常用一股密封流来清洗腔体。外横流、空腔流和密封流之间的相互作用是复杂的,涉及到各种尺度的湍流不稳定和流动不稳定,这是雷诺平均方法无法解决的。为了解决这一复杂问题,本研究采用了壁面大涡模拟(WMLES)方法。在模拟中,采用20°扇形模型,并受到均匀的预旋外横流和径向密封流的影响。它是由使用剪切应力输运(SST)湍流模型的收敛reynolds -average Navier-Stokes (RANS)结果触发的。在WMLES模拟中,采用Smagoringsky亚网格尺度(SGS)模型。通过求解标量输运方程来模拟腔内的混合输运过程。首先讨论了RANS与WMLES结果的总体流场特征和偏差。RANS和WMLES结果均表现为batchelflow模式,但也存在明显的偏差。在小半径区域的偏差是由于RANS方法在捕获边界层小尺度涡结构方面的不足造成的,而在大半径区域的偏差是由于RANS方法在预测外部横流摄取方面的不足造成的。然后详细讨论了边界层涡旋和外部摄取,重点介绍了相关的流动不稳定性。最后,利用非定常压力振荡信号对外流进入引起的大流量结构进行了分析。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Zhejiang University-SCIENCE A
Journal of Zhejiang University-SCIENCE A 工程技术-工程:综合
CiteScore
5.60
自引率
12.50%
发文量
2964
审稿时长
2.9 months
期刊介绍: Journal of Zhejiang University SCIENCE A covers research in Applied Physics, Mechanical and Civil Engineering, Environmental Science and Energy, Materials Science and Chemical Engineering, etc.
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