跨声速条件下轴对称收扩喷管内外流场的数值研究

Numerical study on combination flow field of axisymmetric convergent-divergent nozzle under transonic and supersonic conditions

采用有限体积法,二阶精度插值的Roe格式对三维流场N-S方程进行空间离散;采用LUSGS隐式时间推进法和多重网格技术加快计算收敛速度;采用不同湍流模型、壁面函数对轴对称喷管内外流场进行三维数值模拟.计算结果与实验数据对比表明,采用涡粘修正的RNG模型,内流场使用增强壁面函数,外流场使用标准壁面函数可以得到准确的计算结果.研究表明:在亚声速条件下,喷管外壁面压力分布随落压比的变化不大;超声速条件下,喷管外壁面激波随着落压比的增大前移.

Finite volume method and second order Roe＇s scheme are employed to discretize the three-dimensional N S equation. Lower-upper symmetric Gauss-Seidel （LUSGS） implicit time stepping method and multigrid technique are employed to accelerate convergent rate. Different turbulence models and wall function are applied to 3D numerical simulation of internal external flow field of axisymmetric nozzle. The comparison with experimental data shows that the most accurate results can be obtained by the means of RNG model coupled with eddy viscosity formula, and by using enhanced wall functions for inner wall treatment and standard wall functions for outer wall treatment. The final calculation data are summa-rized, the pressure distribution of nozzle＇s outer wall at different NPR （nozzle pressure ratio） and Mach numbers are compared under transonic and supersonic conditions.