内嵌火箭的管道流场计算分析

Numerical Analysis of Flowfield in a Duct Embedded Rockets

关键词:  管道火箭  火箭喷流  支板射流  引射  数值模拟

Key words:  Ducted rocket engine  Rocket jet  Strut jet  Ejection  Numerical simulation

摘要:

为了研究管道火箭几何分布、工作条件及流道几何外形对流场和二次来流引射特性的影响，以含双方程 k - ω SST湍流模式的质量平均Navier-Stokes方程为控制方程，对含火箭的管道流场进行了数值模拟，对比研究了管道火箭位置、燃烧室压强对管道流场及二次来流引射特性的影响。结果表明:在管道火箭膨胀喷流没有碰触管道侧壁前，二次来流流量随火箭燃烧室压强的增加而增加，而一旦火箭膨胀喷流边界快速膨胀至流道壁面，被引射来流流量将很难得到进一步增加；随着飞行马赫数的增加，二次来流冲压作用增强，可用来调制管道流场；远场来流静止对应于起飞阶段，正是火箭在最大燃烧室压力(满功率)工作阶段，由此需要较好地解决火箭与管道的尺度匹配问题，否则很难获得相应的增益，内嵌(支板)火箭概念更适用于起飞后的飞行阶段。

Abstract:

In order to investigate the influence on the duct flow fields，ejecting performance by changing the embedded rocket geometric distribution，operational conditions and geometric parameters，the cold flow fields in a duct embedded rockets were simulated numerically by using the Favre-Averaged Navier-Stokes equations with the two-equation k - ω SST turbulence model. The effects of the positions and combustion chamber pressure of embedded rockets on the duct flow field and the secondary flow injection performance were studied comparatively. The results of the calculation of different parameters show that: (1) The secondary flow mass flux grows larger as the combustion chamber pressure of the primary rocket increases as long as the rocket expanding jet current does not attach the duct side wall，after that it is difficult to increase the secondary flow entrainments. (2) As the inflow Mach number increased，ram compression role of the secondary flow becomes important，and it can be used to modulate duct flow field. (3) The embedded rocket operational conditions，which is consistent with the inflow conditions at low vehicle flight speed，could not meet the full power demand of the rocket propelling vehicle at takeoff，and duct embedded rocket concept such as strut jet concept will be more suitable for flight phase excluding takeoff.