标题： 低雷诺数下低压涡轮叶片流动的瞬态增长机制 显示英文标题

标题： Transient growth mechanisms of low Reynolds number flow over a low-pressure turbine blade

摘要： 针对流经周期性布置的T-106/300低压涡轮风扇叶片三维扰动的瞬态增长直接分析被提出。 该方法基于流演化算子关于稳态或周期性基流的奇异值分解。 此分析得出最优增长模态。 先前对该流动几何结构全局模稳定性分析的工作表明流动渐近稳定，这表明非模态解释过渡可能更为合适。 本研究将之前关于稳态基流瞬态增长的调查扩展到更高的雷诺数和周期性基流。 发现最优模态的显著瞬态增长表明了与该配置模态增长相比的一种可能的过渡路径。 检查了最优模态的空间范围和局部化，并讨论了可能的物理触发机制。 发现对于更长的时间和更长的展向波长，剪切层分离激发尾迹模；而对于较短的时间和展向波长，观察到与近尾迹激发相关的较小增长。 显示英文摘要

摘要： A direct transient growth analysis for three-dimensional perturbations to flow past a periodic array of T-106/300 low-pressure turbine fan blades is presented. The methodology is based on a singular value decomposition of the flow evolution operator, linearised about a steady or periodic base flow. This analysis yields the optimal growth modes. Previous work on global mode stability analysis of this flow geometry showed the flow is asymptotically stable, indicating a non-modal explanation of transition may be more appropriate. The present work extends previous investigations into the transient growth around a steady base flow, to higher Reynolds numbers and periodic base flows. It is found that the notable transient growth of the optimal modes suggests a plausible route to transition in comparison to modal growth for this configuration. The spatial extent and localisation of the optimal modes is examined and possible physical triggering mechanisms are discussed. It is found that for longer times and longer spanwise wavelengths, a separation in the shear layer excites the wake mode. For shorter times and spanwise wavelengths, smaller growth associated with excitation of the near wake are observed.