二元保形非对称膨胀喷管流场特性研究

利用数值模拟方法对一种与无人飞行器后体一体化设计的二元保形大宽高比非对称膨胀喷管在地面状态的流场特性进行了研究，获得了尾喷管推力性能和三维流动特征随落压比的变化趋势。结果表明：虽然二元保形非对称膨胀喷管沿横向存在非等强度膨胀，但在研究范围内最佳落压比仍主要取决于上方短膨胀面结束位置面积与喉道面积之比；沿横向不等强度膨胀诱发的二次流及旋涡流动能够增强环境冷流与喷流之间的掺混；在研究的落压比范围内，随着落压比的增加喷管的推力性能变化很缓慢。

Flow field of a 2D integrated asymmetry-expansion nozzle

The flow fields of a 2D UCAV aft-body integrated asymmetry-expansion nozzle in ground condition have been simulated using a numerical approach which had been validated by a NASA experimental data. This study was conducted at nozzle pressure ratios (NPR) from 2.0 to 5.5. Results indicate: (1)In spite of nonuniform expansion at different transverse slices of the UAV aft-body integrated nozzle, the maximum propulsive performance NPR strongly lies on area ratio of upper shorter ramp end location to the throat. (2)The mixture of internal jet and external cold air can be enhanced by secondary flow and vortex, which are induced by the nonuniform expansion at different transverse slices of the UAV aft-body integrated nozzle. (3)As the NPR increases within this study, the propulsive performance of the nozzle varies a little.