Optimized Shroud Design for Axial Turbine Aerodynamic Performance
Optimized Shroud Design for Axial Turbine Aerodynamic Performance
复制标题
DOI：
10.1115/1.2777187
复制
发表时间：
2008-07
影响因子：
1.7
通讯作者：
L. Porreca;A. Kalfas;R. Abhari
中科院分区：
文献类型：
--
作者：
L. Porreca;A. Kalfas;R. Abhari
本文对叶冠设计对轴流式涡轮机空气动力学的影响进行了综合研究。对三种不同的试验情况进行了实验测量和数值模拟，这些情况具有相同的叶片几何形状和叶尖间隙，但不同的围带设计。第一个和第二个测试用例代表完整护罩和非轴对称部分护罩几何形状，而第三个测试用例使用优化的部分护罩。在工业应用中，有时使用部分叶片，以便受益于护罩配置的优点，以及减少叶片上的机械应力。然而，机械考虑和气动性能之间的最佳折衷仍然是一个悬而未决的问题，由于所产生的高度三维非定常流场。在低速轴流式涡轮机设施中测量了气动性能，并表明试验情况之间存在明显差异。此外，稳定和时间分辨的测量与计算分析一起进行，以提高对流场上的护罩几何形状的影响的理解，并量化所产生的额外损失的来源。流场分析表明，从60%叶高跨度到叶尖，围带几何形状的影响是显著的。第一个转子中的叶尖泄漏涡起源于部分围带试验情况，而全围带试验情况仅呈现出弱的固有叶尖通道涡。这导致在随后的第二定子中的二次流发展的显著差异，在这一排中具有变化约1%的相关损失。分析表明，修改后的部分围带设计通过保持该部件的总重量几乎不变，从而保持叶根应力几乎不变，使气动效率显著提高约0.6%。因此，这项工作提出了一个全面的流场分析，并显示了在空气动力学性能的护罩几何形状的影响。
This paper presents a comprehensive study of the effect of shroud design in axial turbine aerodynamics. Experimental measurements and numerical simulations have been conducted on three different test cases with identical blade geometry and tip clearances but different shroud designs. The first and second test cases are representative of a full shroud and a nonaxisymmetric partial shroud geometry while the third test case uses an optimized partial shroud. Partial shrouds are sometimes used in industrial application in order to benefit from the advantage of shrouded configuration, as well as reduce mechanical stress on the blades. However, the optimal compromise between mechanical considerations and aerodynamic performances is still an open issue due to the resulting highly three-dimensional unsteady flow field. Aerodynamic performance is measured in a low-speed axial turbine facility and shows that there are clear differences between the test cases. In addition, steady and time resolved measurements are performed together with computational analysis in order to improve the understanding of the effect of the shroud geometry on the flow field and to quantify the sources of the resultant additional losses. The flow field analysis shows that the effect of the shroud geometry is significant from 60% blade height span to the tip. Tip leakage vortex in the first rotor is originated in the partial shroud test cases while the full shroud case presents only a weak indigenous tip passage vortex. This results in a significant difference in the secondary flow development in the following second stator with associated losses that varies by about 1% in this row. The analysis shows that the modified partial shroud design has improved considerably the aerodynamic efficiency by about 0.6% by keeping almost unchanged the overall weight of this component, and thus blade root stresses. The work, therefore, presents a comprehensive flow field analysis and shows the impact of the shroud geometry in the aerodynamic performance.