A linear aerospike nozzle is a kind of altitude adaptive nozzle that has optimum performance over the entire operational range. In this work, flow characteristics of a linear plug nozzle and a truncated plug with 40% plug length are studied numerically. Different flow types associated with an increase in nozzle pressure ratio, corresponding wall pressure variation and shock patterns are studied. The effect of base pressure improvement with a secondary flow from the base (base bleed) of the truncated nozzle is also examined. Four base bleed points are considered, and the optimum bleed point is selected based on performance and base pressure improvement. The two-dimensional numerical model is solved using Reynolds-averaged Navier–Stokes equations with the Transition SST turbulence model. Validation shows that the present model is good enough at predicting the flow features associated with a linear plug nozzle. From the three different flow types associated with this nozzle, the transition from one type to other happens at lower nozzle pressure ratios with truncation due to the reduction in length of the plug. Thrust coefficient increased by 3.54% in the case of the bleed 3 configuration with a secondary flow of 2% of inlet mass flow rate when compared with 40% plug length without base bleed.

线性气钉喷嘴是一种高度自适应喷嘴，在整个操作范围内都具有最佳性能。在这项工作中，线性塞喷嘴和具有 40% 塞长度的截头塞的流动特性进行了数值研究。研究了与喷嘴压力比增加相关的不同流动类型、相应的壁压力变化和冲击模式。还研究了来自截断喷嘴的底部（底部排气）的二次流对底部压力改善的影响。考虑了四个基础泄放点，并根据性能和基础压力改进选择最佳泄放点。二维数值模型使用 Reynolds 平均 Navier-Stokes 方程和 Transition SST 湍流模型求解。验证表明，本模型在预测与线性塞喷嘴相关的流动特征方面足够好。从与该喷嘴相关的三种不同的流动类型中，从一种类型到另一种类型的过渡发生在较低的喷嘴压力比下，并且由于塞子长度的减少而被截断。与 40% 的阀塞长度相比，没有基础泄放的情况下，在带有 2% 入口质量流量的二次流量的泄放 3 配置的情况下，推力系数增加了 3.54%。