摘要
采用高温、高速摩擦点燃法研究Ti_(3)Al基合金在220~380 m/s气流环境中的起燃行为,结合理论计算分析气流速度对表面氧浓度、氧化控制步骤的影响,探讨气流速度对起燃行为的影响机理。结果表明:当气流速度达到240 m/s时,Ti_(3)Al基合金开始发生起燃;当气流速度达到360 m/s时,Ti_(3)Al基合金不再发生起燃。低气流速度下,高温下的表面氧浓度低于临界值,氧化反应控制步骤由低温下的化学动力学过程转变为高温下的氧向合金表面的扩散过程。随着气流速度的加快,虽然对流散热速率增大,但表面氧浓度增大引起的氧化产热速率的增大速率比对流散热速率的大,使得升温速率增大,促进Ti_(3)Al基合金发生起燃。高气流速度下,高温下的表面氧浓度仍然高于临界值,氧化反应控制步骤始终是化学动力学过程。随着气流速度的增大,高温下的氧化产热速率增大速率比对流散热速率的小,使得升温速率减小,不利于Ti_(3)Al基合金发生起燃。
The ignition behavior of Ti_(3)Al-based alloy in 220-380 m/s gas flow environment was studied by using friction ignition method. Combined with numerical calculations, the influence of airflow velocity on surface oxygen concentration and oxidation control step was analyzed, and then the influence of airflow velocity on ignition behavior was discussed. The results show that the Ti_(3)Al-based alloy begins to ignite when the airflow velocity reaches 240 m/s. When the airflow velocity reaches 360 m/s, the Ti_(3)Al-based alloy no longer ignites. Under low airflow velocity conditions, the surface oxygen concentration at high temperature is lower than the critical value, and the oxidation reaction control step changes from the chemical kinetics process at low temperature to the diffusion process of oxygen to the alloy surface at high temperature. As the airflow velocity increases, although the convective heat dissipation rate increases, the increase rate of the oxidation heat generation rate caused by the increase of the surface oxygen concentration is greater than that of convective heat dissipation rate, which increases the heating rate and promotes the ignition of Ti_(3)Al-based alloy. Under high airflow velocity conditions, the surface oxygen concentration at high temperature is still higher than the critical value, and the control step of the oxidation reaction is always the chemical kinetics process. At this time, with the increase of airflow velocity, the increase rate of oxidation heat generation rate at high temperature is smaller than that of convective heat dissipation rate, resulting in a decrease in heating rate, which is not conducive to the ignition of Ti_(3)Al-based alloy.
作者
邱越海
弭光宝
李培杰
隋楠
曹京霞
QIU Yuehai;MI Guangbao;LI Peijie;SUI Nan;CAO Jingxia(Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;National Center of Novel Materials for International Research,Tsinghua University,Beijing 100084,China)
出处
《材料工程》
EI
CAS
CSCD
北大核心
2024年第5期17-25,共9页
Journal of Materials Engineering
基金
国家自然科学基金“叶企孙”科学基金(U2141222)
国家科技重大专项(J2019-Ⅷ-0003-0165)。
