Performance study of bypass dual throat nozzle based on numerical simulation

Abstract This study investigates the aerodynamic performance of elliptical cross-section bypass double-throat nozzles (BDTNs) with varying short-to-long axis ratios (b/a = 1.0, 0.8, 0.6, 0.4), using an axisymmetric BDTN as a reference. Three-dimensional numerical simulations were conducted to analyze flow field structures and performance in both non-vectored and vectored states under fixed inlet conditions (300 K, throat area ratio 1:1.44). The research integrates shaped cross-section design into BDTNs, aiming to improve thrust efficiency and infrared stealth capability. Results show that in the non-vectored state, thrust coefficients peak at NPR = 6, with elliptical BDTNs outperforming axisymmetric ones as b/a decreases. In the vectored state, however, thrust coefficient and vector angle generally decline with smaller b/a. Notably, placing the bypass channel along the short axis markedly enhances vectoring performance: for b/a ≥ 0.6, vector angles exceed 8° and may reach above 20°, while thrust coefficients remain comparable to axisymmetric designs. Oblique secondary flow injection exhibits similar but weaker trends than axial injection. Overall, the b/a = 0.6 configuration offers the best balance between thrust enhancement and flow efficiency. These findings provide new insights into geometric optimization of BDTNs and offer practical guidance for the design of efficient, stealth-capable aero-vector nozzles.