Flow Separation over the surface of the airfoil affect the aerodynamic performance of airfoil, flow separation increases drag and decreases lift. Aerodynamic efficiency of an airfoil can be improved by delaying separation, which increases the lift force and reduces the drag force. Flow separation can be controlled by altering boundary layer behavior such as reducing boundary layer thickness and increases maximum velocity over the surface of an airfoil, these can be done by modifying the geometry of airfoil or other active flow control techniques and passive flow control techniques. In this research, E398 airfoil was selected for analysis. Analysis has been carried out on smooth and modified E398 airfoil, airfoil modified with single bump centered at 0.05C, 0.1C, 0.15C, 0.2C, and 0.3C from leading edge, chord length of an airfoil is 0.128m. The numerical study has been carried out by using Ansys Fluent 14.0 over Smooth and Uni-Bump E398 airfoil, at low Reynolds Number ranging from 18000 to 54000 and Angle of Attack from 00 to 150. Numerical Results show that the aerodynamic efficiency of a modified airfoil with bump centered at 0.1C is higher as compared to smooth airfoil at Reynolds 18000 and 36000. When Reynolds number is 54000, aerodynamic efficiency of a smooth airfoil is higher than the modified airfoil with a single bump at 0.1C. Analysis has been performed by changing the location of bump from 0.5C to 0.3C aerodynamic performance decreases as bump shifted toward the maximum thickness of airfoil because suction pressure decreases on the upper surface of an airfoil. It is observed that as a bump near leading edge of the airfoil, shows the higher aerodynamic performance, the suitable locations of the bump are at 0.5C and 0.1C from leading edge.