Analysis of nonlinear aeroelastic interactions during forced response of coupled turbine blades

耦合涡轮叶片受力响应过程中的非线性气动弹性相互作用分析

• 批准号: 382141955
• 负责人: Dr. Christian Frey
• 金额: --
• 依托单位: Institut für Luftfahrtantriebe (ILA)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/382141955?language=en
• 关键词: Analysis; nonlinear; aeroelastic; interactions; during

The flutter stability represents a dominant constraint in the design of modern low pressure turbines. An important reason for this is that the shape optimization has lead to slender, twisted blades with small chord-to-length ratio, which are known for their susceptibility to flutter. The saturation behavior of flutter vibrations is determined by structural and fluid dynamical nonlinearities, in particular the contact boundary conditions in mechanical joints and unsteady flow phenomena including shocks and stall.The primary goals of the project are(a) to develop methods for the coupled simulation of steady-state flutter and the prediction of the global aeroelastic stability, and(b) to understand the essential effects of nonlinear interactions.For the first time, the question is addressed whether there are configurations that do not flutter for sufficiently small perturbations around the equilibrium, but undergo aeroelastic self-excitation caused by nonlinear effects in the case of larger disturbances (nonlinear instability). Fundamental findings shall be gained concerning the conditions under which nonlinearities in the respective physical domain have a significant influence, and when they contribute to the onset and saturation of self-excited vibrations. Only on the basis of these findings, simplified methods for the flutter analysis can be developed and the error potential of present approaches can be estimated.The focus of the project is flutter of low pressure turbine blades. The mainly considered nonlinearities in the structural domain are the contact interactions in shroud joints, and in the fluid domain, stall and shocks under transonic conditions are considered as causes of strongly unsteady and, thus, nonlinear effects.

颤振稳定性是现代低压涡轮机设计中的主要约束。一个重要的原因是形状优化导致了弦长比小的细长扭曲叶片，这是众所周知的颤振敏感性。颤振振动的饱和特性是由结构和流体动力学非线性决定的，特别是机械接头中的接触边界条件和包括激波和失速在内的非定常流动现象。该项目的主要目标是：（a）开发稳态颤振耦合模拟和整体气动弹性稳定性预测的方法;和（B）理解非线性相互作用的本质效应。第一次提出了这样一个问题，即是否存在对于平衡点附近足够小的扰动不发生颤振的构型，但在较大扰动（非线性不稳定性）的情况下经受由非线性效应引起的气动弹性自激。应获得有关条件下，在相应的物理域的非线性有显着的影响，以及当它们有助于自激振动的开始和饱和的基本调查结果。只有在这些研究结果的基础上，才能发展颤振分析的简化方法，并能估计现有方法的误差潜力。本项目的重点是低压涡轮机叶片的颤振。在结构域中主要考虑的非线性是围带接头中的接触相互作用，而在流体域中，跨音速条件下的失速和激波被认为是强非定常和非线性效应的原因。