某型发动机火焰筒非均匀温度场下热应力分析

【作者】 郭运强；

【导师】 张克实；

【作者基本信息】 西北工业大学 ， 固体力学， 2004， 硕士

【摘要】 燃气涡轮发动机火焰筒在非均匀温度场的作用下，材料会呈现复杂的力学行为，导致使用过程中出现裂纹而造成故障。为探讨火焰简裂纹萌生的条件和原因，本文以现役某型进口军用航空发动机火焰筒为对象，对稳态和瞬态温度场下火焰筒的应力场及其对裂纹萌生的影响进行了分析，主要结论如下： 1．在忽略瞬态升温过程得到的稳态温度场作用下，火焰筒的热应力不足以导致裂纹萌生，所以仅进行稳态分析不能得到合理的结论。 2．对稳态温度场下的蠕变松弛计算表明，高温下的蠕变松弛促使火焰筒的热应力下降，在所考虑的条件下稳态温度场导致火焰筒的蠕变变形不是火焰筒破坏的主要原因。 3．本文重点对发动机起动过程中瞬态温度场导致的热应力进行了分析。分析表明，起动过程中由于热传导滞后引发的温度梯度可以导致火焰筒气膜唇边在起动瞬间发生较大的压缩塑性应变，进而使得该区域在工作时承受较高水平的拉伸应力，高的拉应力会导致火焰筒萌生裂纹。分析也表明，若在起动过程中筒壁的温度梯度较为平缓，火焰筒的气膜唇边在起动完成后始终受微小的压应力作用，火焰筒的寿命可以大大延长。本文研究结果可为发动机火焰筒的维修和改进设计提供参考。更多还原

【Abstract】 The combustor of gas turbine engine operates under inhomogeneous high temperature, which causes very complicated mechanical behavior of combustor’s material, and makes combustor failure. In this thesis, in order to search the condition and reason of failure for a combustor, thermal stress was analyzed in steady and transient temperature field.According to the investigation, three conclusions are obtained.1. The combustor don’t fail if transient rise of temperature field is neglected, the stress field of combustor cann’t cause gas film wall rupture.2. Combustor’s creep and relaxation is calculated in steady temperature field, the results show that creep and relaxation is not main reason destroying combustor chamber.3. Transient thermal field and coupled thermal stress in engine start-up is especially analyzed in this thesis. If there are high temperature gradient between cool liner and hot liner, compressive plastic strain appear at that transient time, which lead to gas film wall bearing high tensile stress at high temperature. High tensile stress is one of main reasons which destroy combustor. On the contrary, if temperature gradient is relatively low, combustor only undergo low compressive stress at high temperature. The combustor of engine has a longer life length.These results can provide some reference for maintain and design for gas turbine combustor.更多还原