接触状态对叶根轮槽应力分布影响的研究

On the Effect of Contact State on Stress Distribution in Turbine Blade Root Wheel Groove Area

汽轮机叶片叶根、轮槽连接区域常因加工误差及磨损等原因导致接触状态的改变,从而改变整个区域应力分布并大大降低汽轮机的使用寿命。本文运用数字光弹性技术实验测试了长叶片叶根、轮槽在不同接触状态下的应力分布情况,同时结合有限元进行了仿真计算。结果表明,叶根、轮槽对称接触时,全部齿同时接触的应力集中系数最小且分布较均匀;而当部分接触齿产生间隙时,接触状态发生显著变化,应力集中系数明显增大;尤其是当左右齿非对称接触时,最大应力集中系数明显增大且应力分布不均匀。本文研究可为叶根、轮槽的优化设计、加工以及叶片的装配、维护提供实验依据。

Contact state change in the area connecting blade root with wheel groove in steam turbine due to machining error and wear etc. may change the stress distribution of whole area and thereby greatly reduce the service life of steam turbine. In this paper, stress distribution in the area connecting long blade root and wheel groove was experimentally measured in different contact states, based on digital photoelasticity technique, and FEM numerical simulation. Results show that when blade is symmetrically contacted with wheel groove, all teeth contact simultaneously, the stress concentration factor is the smallest and its distribution is uniform. But when gaps exist between parts of teeth, the contact state changes obviously, the stress concentration factor increases greatly. Especially, when the left and right teeth contact asymmetrically, the maximum stress concentration factor increases obviously and the stress distribution is nonuniform. Above results can be helpful to optimization of design, processing, assembling and maintenance of blade root and wheel groove in steam turbine.