Background: Tracheal stenosis is a narrowing condition of the trachea that can lead to life threatening breathing complications depending on the extent of reduction in the airway diameter. This condition affects not just the lung’s performance to draw air during inspiration but also the flow behavior in the bronchi generations. Methods: Computational simulations were performed in idealistic healthy and stenosed tracheobronchial models of adult and infant airways consisting of the trachea and mainstem bronchi alone. Effect of 70% reduction in trachea diameter was investigated for both models using Ansys Fluent. Results: We realized that while airflow developed along the center in the healthy model, flow in the stenosed tracheae moved in a jet-like manner, forcing its way across the airway tract with velocity 5 m/s greater than that in the healthy airways. This high jet-like flow at the center in the stenosed tracheae led to high flow impact at the bronchi bifurcation. Consequently, wall shear stress at the bifurcation was high in both stenosis cases. Conclusion: This study shows that tracheal stenosis potentially leads to high flow impact and wall shear stress at the bifurcation of mainstem bronchi, and this effect will have severe consequences in infants than adults.