Rub-in processes in turbines - experimental investigation and modeling

要实现燃气轮机的高效率，需要最小化转子和定子之间的间隙。由于热膨胀或动态载荷等原因，间隙在运行过程中不断变化。在整个运行周期中缺乏间隙控制导致频繁的摩擦，这可能会严重损坏转子和定子，例如以磨损或破裂的形式出现。为了保证整个发动机的高运行安全性和高效率，需要坚固的密封系统，能够容忍甚至是严重的摩擦过程。定子上带有特殊蜂窝衬里的迷宫密封能够满足这些要求。然而，这种密封件的摩擦过程还不完全清楚，这仍然阻碍了可靠设计的开发。因此，在第一个资助期内，建立了一个试验台，用于确定摩擦参数对所产生的接触力、温度和磨损的影响。实验研究的结果和对参与材料Haynes 214和Hastelloy X的热物理材料性质的确定使得能够开发和验证用于模拟摩擦事件的多尺度模拟系统。第二个资助期的目标是进一步发展多尺度有限元模型，以预测复杂密封系统的行为。为此，有必要将蜂窝衬里焊接方法的影响融入到物理描述中，并在实验研究中加以考虑。所获得的摩擦试验台的物理材料特性和试验结果将纳入多尺度有限元模型。因此，该模型可以作为一个重要的工具来完成给定规格规格的迷宫密封系统的设计，并为未来提供可靠的性能和使用寿命预测。

Achieving high efficiency in gas turbines requires the minimization of clearances between rotor and stator. Clearances vary constantly during operation due to e.g. thermal expansion or dynamic loads. The lack of clearance control over the entire operation cycle leads to frequent rubbing, which can critically damage rotor and stator, e.g. in the form of wear or cracking. In order to guarantee high operation safety and efficiency of the entire engine, robust sealing systems are required which are able to tolerate even heavy rubbing processes. Labyrinth seals with special honeycomb liners on the stator are able to meet these requirements. However, rubbing processes in such seals are not completely understood yet, which still prevents the development of a reliable design. Therefore, during the first funding period, a test rig was set up and used to determine the influence of rubbing parameters on resulting contact forces, temperatures and wear. The results of the experimental investigation and the determination of thermo-physical material properties of the participating materials Haynes 214 and Hastelloy X enabled the development and validation of a multiscale modelling system for simulating a rubbing event. It could be shown that the manufacturing process has a significant influence on physical material properties and the rubbing process.The aim for the second funding period is to further develop the multiscale finite element model in order to predict the behavior of complex sealing systems. For this, it is necessary to integrate the influence of the soldering method of honeycomb liners into the physical description and to consider it in the experimental investigation. The obtained physical material properties and experimental results of the rub test rig will be incorporated into the multiscale finite element model. Thus, the model serves as an important tool to completely design labyrinth sealing systems for given specification profiles and to provide reliable performance and service life prognoses in the future.