几何参数对多股流 S 弯喷管流动特性的影响

The geometric design parameters exert a significant influence on the flow characteristics of multi-stream serpentine nozzles，including multi-stream mixing performance. To investigate the variation pat⁃ terns of nozzle flow characteristics with geometric parameters，numerical simulations were conducted for multi-stream serpentine nozzles with different throat aspect ratios and offset ratios. The results demonstrate that the throat aspect ratio governs the pressure differential variation in the mixing section to regulate flow mixing effec⁃ tiveness. Higher throat aspect ratios reduce the pressure difference between the lower wall surface and main flow in the mixing section，leading to decreased flow deflection angles. This enhances mixing completeness in the up⁃ per flow region and intensifies vortex pairs generated in the shear layer. Considering combined effects of vortex losses，frictional losses，and shock losses，the total pressure recovery coefficient and main flow coefficient reach maximum values at a throat aspect ratio of 5. The axial thrust coefficient initially increases then decreases domi⁃ nated by jet deflection angles and mixing losses with ambient atmosphere. The offset ratio influences flow mixing by controlling longitudinal curvature of the nozzle. Larger offset ratio increases main flow deflection angles，inten⁃ sifies compression effects on the upper tertiary flow，and strengthens spotted vortices in the shear layer. The in⁃ creased vortex losses，frictional losses，and shock losses collectively reduce total pressure recovery coefficient and main flow coefficient by over 2%. Augmented jet deflection angles result in a 1.55% reduction of axial thrust coefficient.