Research on aerodynamic performance of a dorsal S-shaped stealth inlet with irregular-shaped lip

Abstract Numerical simulation was adopted in this paper to optimize the aerodynamic performance of the inlet by investigating various irregular-shaped lips. The results show that when the upper lip is V-shaped, upper pair vortices significantly degrades the low-speed performance, leading Δ σ 0 ̅ $\Delta ̅{{\sigma }_{0}}$ up to 6.73 % at the outlet of the duct; when the upper lip is M-shaped, the low-speed performance is improved with Δ σ 0 ̅ $\Delta ̅{{\sigma }_{0}}$ less than 4 %, which satisfies the engine-inlet matching requirements. When the lower lip is V-shaped, a backflow phenomenon is induced at the lower V-shaped lip under high-altitude-speed condition, resulting in a Δ σ 0 ̅ $\Delta ̅{{\sigma }_{0}}$ of 3.92 % at the inlet outlet; the backflow phenomenon still exists when the lower lip is M-shaped. Only when the upper lip is M-shaped and the lower lip is inverted V-shaped can the inlet achieve excellent low-speed performance and outstanding high-speed performance simultaneously.