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首页> 外文期刊>The Aeronautical Journal >Turbine thermomechanical modelling during excessive axial movement and overspeed
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Turbine thermomechanical modelling during excessive axial movement and overspeed

机译：过度轴向运动和超速时的涡轮热力学建模

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This manuscript discusses the numerical (finite element) and analytical modelling of structural interactions between gas turbine components in case of excessive axial movement and overspeed. Excessive axial movement, which may occur after a shaft failure, results in contact between rotating and static turbine components under high forces. These forces create friction which can act as a counter torque, potentially retarding the 'free-rotating' components. The study is based on a shaft failure scenario of a 'three-shaft', high 'bypass' ratio, civil 'large-fan' engine. Coupled analytical performance and friction methods are used as stand-alone tools to investigate the effect of rubbing between rotating and stationary components. The method is supported by 'high-fidelity', 'three-dimensional', thermomechanical finite element simulations using LS-DYNA software. The novelty of the work reported herein lies in the development of a generalised modelling approach that can produce useful engine design guidelines to minimise the terminal speed of a free running turbine after an unlocated shaft failure. The study demonstrates the advantage of using a fast analytical formulation in a design space exploration, after verifying the analytical model against finite element simulation results. The radius and the area of a stationary seal platform in the turbine assembly are changed systematically and the design space is explored in terms of turbine acceleration, turbine dislocation rate and stationary component mass. The radius of the friction interface increases due to the increasing radius of the nozzle guide vane flow path and stationary seal platform. This increases the frictional torque generated at the interface. It was found that if the axial dislocation rate of the free running turbine wheel is high, the resulting friction torque becomes more effective as an overspeed prevention mechanism. Reduced contact area results in a higher axial dislocation rate and this condition leads to a design compromise between available friction capacity, during shaft failure contact and seal platform structural integrity.
机译：该手稿讨论了在过度轴向运动和超速情况下燃气轮机组件之间的结构相互作用的数值（有限元）和分析模型。轴故障后可能发生的过度轴向运动会导致旋转和静态涡轮机部件在强力作用下接触。这些力产生摩擦，该摩擦可以充当反扭矩，从而可能阻碍“自由旋转”组件。该研究基于“三轴”，高“旁路”比，民用“大风扇”发动机的轴故障情况。耦合的分析性能和摩擦方法被用作独立工具来研究旋转和固定组件之间的摩擦效果。使用LS-DYNA软件的“高保真”，“三维”，热机械有限元模拟支持了该方法。本文报道的工作的新颖性在于开发了一种通用的建模方法，该方法可以产生有用的发动机设计指南，以使未定位的轴故障后空转涡轮的终端速度最小化。在针对有限元仿真结果验证了分析模型之后，该研究证明了在设计空间探索中使用快速分析公式的优势。涡轮机组件中固定密封平台的半径和面积得到系统地更改，并根据涡轮机加速度，涡轮机错位率和固定组件质量来探索设计空间。摩擦界面的半径由于喷嘴导向叶片流路和固定密封平台的半径增加而增加。这增加了在界面处产生的摩擦扭矩。已经发现，如果自由运转的涡轮的轴向错位率高，则作为超速防止机构，所得的摩擦转矩变得更加有效。减小的接触面积会导致较高的轴向错位率，并且这种情况会导致在轴故障接触期间可用的摩擦力与密封平台结构完整性之间的设计折衷。

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