Modulation and Radial Migration of Turbine Hub Cavity Modes by the Rim Seal Purge Flow
Modulation and Radial Migration of Turbine Hub Cavity Modes by the Rim Seal Purge Flow
复制标题
DOI：
10.1115/1.4034416
复制
发表时间：
2016-06
影响因子：
1.7
通讯作者：
R. Schädler;A. Kalfas;R. Abhari;G. Schmid;S. Voelker
中科院分区：
文献类型：
--
作者：
R. Schädler;A. Kalfas;R. Abhari;G. Schmid;S. Voelker
在本文中，轮毂空腔模式及其迁移到主环空流的实验和数值研究的结果。在轴流式涡轮机试验装置上，对一个一级半、无围带、高负荷、具有三维成形叶片和圆柱形端壁的轴流式涡轮机结构进行了试验。叶片设计和边缘密封吹扫流路都是现代高压燃气轮机的代表。用快速响应气动探针（FRAP）测量了两种不同边缘密封吹扫流量下轮毂空腔出口区域的非定常流场。此外，快速响应的壁挂式压力传感器已安装在空腔内。为了补充实验工作，采用了非定常全环空计算流体动力学（CFD）模拟。轮毂腔内的时间分辨压力测量结果显示出明显的空腔模式，该模式显示出对边缘密封吹扫流量注入量的强烈依赖性。数值预测提供了这些模式的起源信息，并将它们与周围的明显摄入点。边缘密封界面处的非定常探针测量结果表明，轮毂空腔诱导模式的特征迁移到主环空流中，直至叶片翼展的30%。在此基础上，发现了一种气动损失机理，表明通过降低边缘密封吹扫流量来降低损失的益处被涡轮机轮毂空腔模式的存在所削弱。
In the present paper, the results of an experimental and numerical investigation of the hub cavity modes and their migration into the main annulus flow are presented. A one-and-a-half stage, unshrouded and highly loaded axial turbine configuration with three-dimensionally shaped blades and cylindrical end walls has been tested in an axial turbine facility. Both the blade design and the rim seal purge flow path are representative to modern high-pressure gas turbines. The unsteady flow field at the hub cavity exit region has been measured with the fast-response aerodynamic probe (FRAP) for two different rim seal purge flow rates. Furthermore, fast-response wall-mounted pressure transducers have been installed inside the cavity. Unsteady full-annular computational fluid dynamics (CFD) simulations have been employed in order to complement the experimental work. The time-resolved pressure measurements inside the hub cavity reveal clear cavity modes, which show a strong dependency on the injected amount of rim seal purge flow. The numerical predictions provide information on the origin of these modes and relate them to pronounced ingestion spots around the circumference. The unsteady probe measurements at the rim seal interface show that the signature of the hub cavity induced modes migrates into the main annulus flow up to 30% blade span. Based on that, an aerodynamic loss mechanism has been found, showing that the benefit in loss reduction by decreasing the rim seal purge flow rate is weakened by the presence of turbine hub cavity modes.