流-固-摩擦耦合作用带冠叶片振动响应特性研究

In the design of aero engine turbine blades, dry friction induced by dynamic contact of shroud dampers is one of the most important mechanisms to dissipate the vibration energy and reduce vibration stresses. The numerical solution of vibration of turbine blades involving dry friction between the shrouds in unsteady flow has been a great challenge in computational mechanics for decades. It places exact demand on robust and efficient numerical solvers, physics-based friction models and high performance computing. Current state-of-art analytical and numerical approaches model the flow-induced vibration of blades by imposing the fluid as simplified boundary conditions and ignoring the strong coupling between the unsteady flow and large displacement blade systems. In addition, it is a commonplace to apply empirical static friction models to the shroud dampers to study the effects of dry friction on the dissipation of vibration energy. Nevertheless, the lack of physics-based dynamic friction models and fail to model the complex fluid-structure interactions in the conventional methods result in unrealistic predictions of the dynamic response and various vibration modes of turbine blades in unsteady flow. In the proposed project, a monolithic Lagrangian meshfree method and a material point meshless friction model will be establishmented to analysis the vibration response characteristics of shrouded turbine blade system under the coupling effect of “Fluid-Structure-Friction”. The proposed monolithic Lagrangian meshfree method provide us a unique capability to simulate the flow-induced vibration of blades by solving a strongly coupled fluid-structure interaction problem using high performance computing clusters. Furthermore, we propose to develop a physics-based friction model to predict the dynamic contact forces as well as their influence on the vibration mode of the blades. It is anticipated that the development of the novel numerical methods and high-fidelity contact models enables a more accurate description of the turbine blades physical working environment, and provides guideline and computational tools for the design and development of aero-engine turbine blades.

涡轮叶片因非定常流动而诱发的强迫振动，是造成涡轮高周疲劳损伤的主要原因之一。非定常流场中的带冠涡轮叶片振动是叶片外部绕流、叶片与叶片间的干摩擦阻尼结构共同构成的复杂流固耦合非线性动力学系统的瞬态动力学问题。过去研究多通过简化气流动态激振力或分域法进行解耦求解，与真实的叶片振动存在差异。本项目拟以非定常流动中含干摩擦阻尼的带冠叶片系统为研究对象，综合考虑“流-固-摩擦耦合”作用对系统振动特性的影响，通过建立拉格朗日整体流固耦合数值计算方法和物质点无网格摩擦计算模型，在统一的求解框架整体耦合计算带冠涡轮叶片动态响应，从而深入揭示复杂结构在非定常流动及干摩擦阻尼综合作用下的振动机理与动态响应特性，分析系统关键参数的影响规律；发展具有自主知识产权的针对非定常流动下干摩擦阻尼结构流固耦合问题的数值模拟分析方法，为航空发动机涡轮叶片的设计提供理论依据与高效精确的计算工具。

涡轮叶片因非定常流动而诱发的强迫振动，是造成涡轮高周疲劳损伤的主要原因之一。非定常流场中的带冠涡轮叶片振动是叶片外部绕流、叶片与叶片间的干摩擦阻尼结构共同构成的复杂流固耦合非线性动力学系统的瞬态动力学问题。过去研究多通过简化气流动态激振力或分域法进行解耦求解，与真实的叶片振动存在差异。本项目以非定常流动中含干摩擦阻尼的带冠叶片系统为研究对象，综合考虑“流-固-摩擦耦合”作用对系统振动特性的影响，通过建立拉格朗日整体流固耦合数值计算方法和物质点无网格摩擦计算模型，在统一的求解框架整体耦合计算带冠涡轮叶片动态响应，从而深入揭示复杂结构在非定常流动及干摩擦阻尼综合作用下的振动机理与动态响应特性，分析系统关键参数的影响规律；发展具有自主知识产权的针对非定常流动下干摩擦阻尼结构流固耦合问题的数值模拟分析方法，为航空发动机涡轮叶片的设计提供理论依据与高效精确的计算工具。