This study determines the effect of flow aerodynamics modification on the combustion characteristics of a new miniature combustor. The n-heptane was injected into the combustor at a flow rate of 1.0 ml/min to 2.5 ml/min, and the airflow rate varied between 7.0 l/min and 20.0 l/min at a successive fuel flow rate to maintain the equivalence ratio. The flame was confined in the combustor in the lean fuel regime. The modified combustor stabilized and sustained the flame at a high Reynolds number. This study used a numerical simulation of the isothermal flow to explain the results of the experiment. The recirculation zone at the sidewall bottom chamber extends the combustor operating regime to the higher Reynolds number. This recirculation balanced the flame propagation and flow velocity at higher Reynolds numbers and strengthen the flame anchoring inside the bottom chamber. The modified flow aerodynamics enhanced the combustion sustainability of the miniature combustors. It is a critical parameter in designing new combustors with a wide range of operation regimes at a small scale.