This paper explores through a numerical simulation the laminar bubble separation phenomena using Ansys Fluent and pointwise codes. Under steady regime, pressure based RANS solver was selected with correlation-based intermittency turbulent model in order to predict the boundary layer transition aspect. The aerodynamic profile used in calculation represented an S809 horizontal axis wind turbine airfoil. The numerical tests were carried out for Reynolds number of 0.75 105 and Turbulence intensity of 0.3%. In fact, the presence of the laminar bubble separation required the use of control device to mitigate or delete this separation-reattachment zone and therefore enhancing the aerodynamic performance blade. Original passive control technique was proposed to testify its potential in front of the LSB developed over the two airfoil sides under small angle of attack. The control is fullfiled via tandem Slot within airfoil. The results without control were validated with experimental data and showed a good agreement. Concerning the control, the slotted airfoil has a potential to manipulate the LSB, however, it could not lead to a significant improvement of the aerodynamic performances because of the small size of the LSB.