The ingestion of foreign objects poses a serious threat to the operational safety of aircraft engines. A simulation method for foreign object trajectories was proposed based on the Euler-Lagrange gas-solid two-phase framework. The method incorporated wall collision theory and a non-spherical drag model for bird. Meanwhile, a three-dimensional compressible model of foreign object motion in a ribbed S-shaped intake was established, in which multiple aerodynamic and collision forces were systematically considered. On this basis, the trajectories of two types of foreign objects under different parameters were compared, and their impact characteristics were obtained. The results indicate that birds usually experience two major collisions in the intake, and their exit velocity increases significantly compared with the initial velocity. When the initial velocity is 80 m/s, the maximum velocity increment reaches 34.61%. The upper region near the fuselage side of the entrance is identified as a high-risk ingestion zone, where birds may enter the intake with fewer collisions. The final collision positions of the birds are concentrated near 80% of the blade height on the upper half region of the engine fan close to the fuselage, implying stricter strength requirements for fan blade tips. In addition, sand particles are accelerated by the high-speed airflow along the intake. When the particle size decreases to below 3 mm, the average velocity has increased by more than 100% compared to the initial velocity, with more than 50% of the particles impacting within 0.6 times the fan diameter. It is concluded that the present study provides valuable references for optimizing intake designs and studying foreign object damage.