热障涂层对涡轮动叶温度及应力的影响研究

Effects of Thermal Barrier Coating on Temperature and Stress of Turbine Rotor Blade

关键词:  燃气轮机  涡轮动叶  热障涂层  流热固耦合  温度分布  热应力

Key words:  Gas turbine  Turbine rotor blade  Thermal barrier coating  Fluid-thermo-structure coupling  Temperature distribution  Thermal stress

摘要:

为研究热障涂层对于涡轮叶片服役温度和应力的影响，以燃气轮机第一级涡轮动叶为研究对象，基于流热固耦合的数值仿真方法，分析了有无热障涂层及不同热障涂层厚度下，叶片的流动传热特征以及叶身应力响应变化规律，并将温度和应力分析结果与真实服役叶片热障涂层剥落和基体裂纹萌生失效等故障情况进行对比分析。结果表明：数值仿真方法可以揭示涡轮叶片实际运行中的温度和应力分布特征；热障涂层可有效降低叶片基体的平均温度，但是对于局部高温区，若没有良好的冷却设计配合，热障涂层的保护效果有限；热障涂层厚度变化未改变叶片高应力区位置，随着厚度增加，叶片危险部位的应力逐渐下降；对于本文的研究对象，与无热障涂层情况相比，0.4mm热障涂层可使得叶片高应力区域最大等效应力下降30~60MPa。

Abstract:

In order to study the effects of thermal barrier coating on service temperature and stress of turbine blades， the first-stage turbine rotor blade of a gas turbine was taken as the research object. Utilizing numerical simulation method based on fluid-thermo-structure coupling， the characteristics of flow and heat transfer and the variation of the blade stress response were compared and analyzed under different thickness of thermal barrier coating. The temperature and stress analysis results were compared with the damages of the actual service blade such as the spalling of the thermal barrier coating and crack initiation on the blade substrate. The results show that the numerical simulation method can reveal the temperature and stress distribution characteristics of the turbine blade in actual operation.The thermal barrier coating can effectively reduce the average temperature of the blade substrate， but for the local high temperature area， if there are flaws in the air cooling design， the protective effect of thermal barrier coating is limited. Changes of thermal barrier coating thickness do not change the weak position of blade stress. As the thickness increases， the stress in the dangerous part of the blade gradually decreases. For the research object of this paper， compared with bare blade， thermal barrier coating with a thickness of 0.4mm can reduce the maximum equivalent stress in the high stress region of the blade by 30 to 60MPa.