用线性化计算跟踪扼流圈颤振不稳定源
Choke flutter instability sources tracking with linearized calculations
摘要：
目的：涡轮喷气发动机中的阻流颤振是一种流固耦合现象，它会导致风扇或压气机叶片的失效。在超高涵道比风扇中，当强激波对叶片通道造成阻塞时，在部分速度区域和低冲角或负冲角下会出现阻塞颤振。主要激励源的定位和不同的功交换机制的理解将有助于避免缺陷和危险的风扇设计。设计/方法/途径：在本文中，一个UHBR风扇分析使用时间线性化的雷诺平均纳维-斯托克斯方程求解器来调查扼流颤振。选择稳定状态和施加的振动（叶片间相位角、折合频率和模态），使其处于扼流颤振状态。由线性化引起的叠加原理允许将叶片分解成许多小的子部分，以跟踪每个局部振动对全局阻尼的贡献。所有模拟均在2D叶片到叶片提取上进行。结果：结果分析指出，在后缘的激励源的数量有限，这引起了很大一部分的工作交换在有限的区域的翼型。主要现象是激波运动和激波/边界层相互作用。独创性/价值：一个原始的激励源跟踪方法允许的线性化计算解决和应用到UHBR风扇测试案例。
英文摘要：
Purpose :The choke flutter is a fluid-structure interaction that can lead to the failure of fan or compressor blade in turbojet engines. In Ultra High Bypass Ratio (UHBR) fan, the choke flutter appears at part speed regimes and at low or negative incidence when a strong shock-wave chokes the blade to blade channel. Localization of main excitation sources and the understanding of the different work exchange mechanisms will help to avoid deficient and dangerous fan design. Design/methodology/approach :In this paper, an UHBR fan is analyzed using a time-linearized Reynolds-Averaged Navier-Stokes equation solver to investigate the choke flutter. The steady state and the imposed vibration (inter blade phase angle, reduced frequency and mode shape) are selected to be in choke flutter situation. Superposition principle induced by the linearization allow to decompose the blade in numerous small subsections to track the contribution of each local vibration to the global damping. All simulations have been performed on a 2D blade to blade extraction. Findings :Result analysis points to a restricted number of excitation sources at the trailing edge which induce a large part of the work exchange in a limited region of the airfoil. Main phenomena suspected are the shock-wave motion and the shock-wave/boundary layer interaction. Originality/value :An original excitation source tracking methodology allowed by the linearized calculation is addressed and applied to a UHBR fan test-case.
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