Linear Stability of the flow past a low pressure turbine blade
Linear Stability of the flow past a low pressure turbine blade
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通过低压涡轮叶片的流动的线性稳定性
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
V. Theofilis
中科院分区：
文献类型：
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作者：
Nadir Abdessemed;S. Sherwin;V. Theofilis
本文研究了低压涡轮机（LPT）叶栅中的线性双全局不稳定性。特别是使用Floquet理论和高阶谱/hp-元方案研究了T106/3叶片二维时间周期基本状态的三维不稳定性，用于基本流动和不稳定性计算。在本项目早期工作的框架中，已经确定了稳定到时间周期流的二维分叉。本文的Floquet分析表明，时间周期流在二维转捩后不久就变成三维不稳定流。已经确定了两种重要的模式，与分离气泡和基本状态的尾流有关。初始化的三维DNS上确定的Floquet本征模在低振幅证实了线性稳定性分析的结果。除了完成的特征值为基础的分析，有史以来第一次瞬态增长的结果，基本上是非平行流已经获得。特别是，所考虑的流的伪谱已被确定，并已揭示了新的机制，表现出潜在的三维过渡作为瞬态增长的结果。
The present work is concerned with linear BiGlobal instabilities of flow in a cascade of Low-pressure turbine (LPT) blades. In particular the three-dimensional instability of twodimensional time-periodic basic states past a T106/3 blade is investigated using Floquet theory and a high-order spectral/hp-element scheme, used for both the basic flow and the instability calculations. The two-dimensional bifurcation of steady to time-periodic flow has been identified in the framework of earlier work on the present project. The present Floquet analysis shows that the time-periodic flow becomes three-dimensionally unstable soon after the two dimensional transition. Two modes of significance have been identified, associated to the separation bubble and the wake of the basic state. Three-dimensional DNS initialized on the identified Floquet eigenmodes at low amplitudes confirms the results of linear stability analysis. Besides the completion of the eigenvalue-based analyses, first-ever transient-growth results of an essentially nonparallel flow have been obtained. In particular, the pseudospectrum of the flow under consideration has been identified and new mechanisms have been revealed, demonstrating the potential for three-dimensional transition as consequence of transient growth.