摘要
钛合金燃烧是现代航空发动机的典型灾难性事故,压气机转子与静子的异常摩擦是主要的着火源.本文基于非均相着火理论建立了考虑摩擦热源的钛合金着火模型,推导了着火温度和着火延迟时间的理论计算公式,进而分析摩擦系数、氧浓度、流速、接触半径以及阻燃层等因素对着火参数的影响规律.结果表明:当摩擦接触区的瞬时温度低于临界生热温度时,生热过程由摩擦热主导;当高于临界生热温度时,生热过程由化学反应热主导.降低摩擦系数可以显著提高着火温度,而摩擦系数的变化对着火延迟时间影响很小.着火温度随着氧浓度的增大和流速的减小均呈明显下降趋势.当氧浓度从21%增加至42%、流速从310 m/s下降至50 m/s时,着火温度分别降低约213 K和197 K.实验结果与理论计算值的相对误差为8.3%,验证了模型的可靠性.阻燃层可以明显提高钛合金的着火温度和着火延迟时间,带阻燃层的钛合金的着火温度提高约172 K,着火延迟时间提高约3 s.
Combustion of titanium alloy is a typical catastrophic failure of modern aeroengine.The abnormal friction between compressor rotor and stator is the main ignition source.A thermal theory model with friction heat source of titanium alloy is established based on the theory of heterogeneous ignition.The corresponding equation of critical temperature and ignition delay time are derived.The difference between the frictional ignition model and the classic model is discussed.The concept of critical heat generation temperature is proposed.The difference from the heterogeneous ignition model,and the effects of friction coefficient,oxygen concentration,flow velocity,contact radius and flame retardant layer thickness on the ignition parameters are analyzed.The research result shows that when the instantaneous temperature of the contact surface is lower than the critical heat temperature,the heat generation process is dominated by frictional heat,and when the temperature is higher than the critical heat temperature,the heat generation process is dominated by chemical reaction heat,that reducing the coefficient of friction can dramatically increase the critical temperature,but the change of friction coefficient has very little effect on the ignition delay time which can be ignored,that the critical temperature decreases significantly with the increase of oxygen concentration and the decrease of flow velocity.When the oxygen concentration increases from 21%to 42%and the flow velocity decreases from 310 m/s to 50 m/s,the critical temperature decreases by about 213 K and 197 K,respectively.The relative error between the experimental result and the theoretical result is 8.3%,which verifies the reliability of the model.The contact area has an effect on friction heat generation,reaction heat generation,and surface heat dissipation,and has a great influence on the critical temperature.The critical temperature decreases exponentially with contact radius increasing.When the contact radius increases to 0.007 m,the ignition temperature of the titanium alloy and its flame retardant layer are 899 K and 988 K,respectively.The increase of the thickness of flame retardant layer can effectively improve the critical temperature and ignition delay time.The critical temperature of titanium alloy with flame retardant layer is increased by about 172 K,and the ignition delay time is increased by about 3 s.
作者
梁贤烨
弭光宝
李培杰
黄旭
曹春晓
Liang Xian-Ye;Mi Guang-Bao;Li Pei-Jie;Huang Xu;Cao Chun-Xiao(Department of Mechanical Engineering,Tsinghua University,Beijing 100084,China;Institute of Titanium Alloy,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;Key Laboratory on Advanced Titanium Alloys of AECC,Beijing 100095,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第21期140-152,共13页
Acta Physica Sinica
基金
国家科技重大专项(批准号:2017-Ⅶ-0012109,j2019-Ⅷ-0003)
国家自然科学基金(批准号:51471155)
中国航发创新基金(批准号:CXPT-2018-36)资助的课题.
关键词
钛合金
摩擦着火模型
非均相反应
阻燃
titanium alloy
ignition model with friction
heterogeneous reaction
fireproof
