超声速电弧喷射器内等离子体流场的数值模拟

NUMERICAL SIMULATION ON THE INTERNAL PLASMA FLOW OF A SUPERSONIC ARCJET

关键词:  电弧喷射发动机  数值仿真  等离子体射流  流动分布

Key words:  Aarjet engine  Numerical simulation  Plasma jet  Flow distribution

摘要:

对一个以氮气为工作气体、在局域热力学平衡下的超声速电弧喷射器内等离子体流场进行了数值模拟。流动模型是耦合了电磁场的扩展Ｎ－Ｓ方程组。电场由电势方程近似反映，只考虑周向自感应磁场。数值方法中， 空间离散格式为中心差分， 用标量耗散模型抑制数值波动。用以经典四阶龙格－库塔法为基本迭代格式的时间推进方法求解控制方程组。电势的迭代计算采用多重网格加速收敛， 用隐式残值光滑技术改善收敛速度以及时间推进过程的稳定性。计算取得初步的成功： 电弧已经出现并可观察到电弧喷射器内的离解和电离状况以及化学不平衡、粘性等效应对流动过程的影响。

Abstract:

The internal flow field of an arcjet using nitrogen as working gas was simulated under the hypothesis of LTE.The flow model was the extended Navier Stokes equation system coupling with the electromagnetic field.The electric field was simulated by electric potential equation.A time stepping scheme using 4th order classical Rouge Kutta method was used to get the result.The electromagnetic field was calculated only in the first Rouge Kutta step and froze in the others,which can reduce the computational load while not affect the convergence characteristic.Other steps including multigrid techniques and residue smoothing were taken to accelerate the convergence rate and improve the calculation stability.The calculation is successful.The arc appear around the axis and characteristics of dissociation and ionization and other phenomenon such as the effects of chemical nonequilibrium and viscosity can be observed.