束缚态特征温度方法及应用

Bound-state characteristic temperature method and its applications

随着高超声速飞行器速度增大,激波层空气等离子体中的原子发射谱线成为辐射加热主要来源,因此研究原子激发非常重要.考虑到处于热非平衡态的空气等离子体,平衡态统计理论不适用.精细物理模型(如碰撞辐射模型)虽然可以处理热非平衡问题且准确度高,但计算量太大,难于工程应用.本文采用束缚态特征温度法,结合FIRE II激波管实验中的非平衡空气等离子体,对原子激发进行了分析.计算得到的原子能级布居与碰撞辐射模型符合,说明简化计算是合理的,计算效率提高了2000倍以上,且能够保证一定的精度.

As the speed of a hypersonic vehicle increases,atomic emission lines in the shock-layer will be a main source of radiative heating.Therefore,it is very important to study the atomic excitation in the air plasma in the shock layer.For a thermal nonequilibrium air plasma,the equilibrium statistical theory is not applicable.Although full models(such as the collisional-radiative model)can be used to solve nonequilibrium problems with high accuracy,they are too expensive computationally and difficult to apply to engineering.In this work,we investigate the atomic excitation in air plasmas by the bound-state characteristic temperature(BCT)method.Some cases of equilibrium and nonequilibrium air plasmas associated with the well-known FIRE II flight experiment are considered.The calculated atomic energy level populations are in good agreement with those from the CR model,thereby showing that our calculation is reasonable and has a good accuracy.The computational efficiency is more than 2000 times higher than that from the CR model.If it is used in the flow field of a hypersonic vehicle,the computational cost can be greatly reduced.