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.

颤动稳定性代表了现代低压涡轮机设计中的主要约束。这样做的一个重要原因是，形状优化导致具有较小的和弦与长度比的细长，扭曲的叶片，这是其易感性的敏感性而闻名的。颤动振动的饱和行为取决于结构和流体动态非线性，特别是机械接头和不稳定流动现象的接触边界条件，包括冲击和失速。解决了是否存在对平衡周围足够小的扰动的配置，但是在较大的干扰（非线性不稳定性）的情况下，由于非线性效应引起的航空弹性自我激发。关于各个物理领域中的非线性具有重大影响以及它们有助于自激发振动的发作和饱和的条件，应获得基本发现。仅在这些发现的基础上，才能开发出简化的扑动分析方法，并且可以估算当前方法的误差潜力。该项目的重点是低压涡轮叶片的颤动。结构结构域中主要考虑的非线性是裹尸布关节中的接触相互作用，在跨性别条件下的流体结构域，失速和冲击中被认为是强烈不稳定的原因，因此是非线性效应。