双温度氩-氮等离子体热力学和输运性质计算

获得覆盖较宽温度和压力范围内的等离子体热力学和输运性质是开展等离子体传热和流动过程数值模拟的必要条件.本文通过联立Saha方程、道尔顿分压定律以及电荷准中性条件求解等离子体组分;采用理想气体动力学理论计算等离子体热力学性质;基于Chapman-Enskog方法求解等离子体输运性质.利用上述方法计算了压力为0.1, 1.0和10.0 atm (1 atm=101325 Pa),电子温度在300—30000 K范围内,非局域热力学平衡(电子温度不等于重粒子温度)条件下氩-氮等离子体的热力学和输运性质.结果表明压力和非平衡度会影响等离子体中各化学反应过程,从而对氩-氮等离子体的热力学及输运性质有较大的影响.在局域热力学平衡条件下,计算获得的氩-氮等离子体输运性质和文献报道的数据符合良好.

Calculation of two-temperature thermodynamic and transport properties of argon-nitrogen plasma

The thermodynamic and transport properties of plasmas over a wide range of temperature and pressure are necessary to model the heat transfer and flow processes in plasma.In this study,the plasma composition is solved by simultaneous Saha equation,Dalton's partial pressure law and charge quasi-neutral equation.The thermodynamic properties of plasma computation are based on the kinetic theory for ideal gas.While the calculation of transport properties is based on the solution of Boltzmann’s equation by the Chapman-Enskog method.The thermodynamic and transport properties of argon-nitrogen plasma at pressures of 0.1,1.0 and 10.0 atm,electron temperatures ranging from 300 to 30000 K,and non-local thermodynamic equilibrium(NLTE),where the electron temperature is not equal to the temperature of heavy particles,,are investigated by using the above method.The results show that the value of non-equilibrium parameter has a great influence on the properties of the argon-nitrogen mixture.With the increase of non-equilibrium parameter,the dissociation reaction requires a higher electron temperature,which leads the dissociation peak to shift to a higher electron temperature.The ionization and dissociation reaction will enter into the high temperature region due to the increase in pressure.This change will affect the peak position and value of the specific heat,viscosity,thermal conductivity and electrical conductivity of plasma.In addition,since the electronic translational thermal conductivity and electrical conductivity mainly depend on the electron number density,when non-equilibrium parameter and pressure increase,the electron number density will increase at high electron temperature,thus improving the electronic translational thermal conductivity and electrical conductivity.Under the condition of local thermodynamic equilibrium,the transport properties of argon-nitrogen plasma obtained by calculation are in good agreement with previously reported data.