The research on gas turbine blade cooling systems is concerned with the fluid flow and heat transfer. Gas turbine blades are cooled internally by supplying cooling air that is routed through the inner passageways. The amount of cooling air, which is dependent on the mass flow rate through the orifice, depends on the discharge coefficient similar to a rotating orifice. Not much research has been carried out in the orifice that rotates. In this paper, CFD simulations are performed on simple rotating orifice using the CFD-ACE+ simulation package. The objectives are to understand the flow mechanism occurring in the rotating orifice and to compare the numerical results with experimental data from published literatures. A model with high number of cells in the mesh to ensure good accuracy is used. The agreement between the CFD simulation using CFD-ACE+ and experimental data are good. The rotating disc caused the flow velocity to be pushed to one side, hence reducing the discharge coefficient. The discharge coefficient in the rotating orifice remains initially constant until the tangential velocity of the rotating disc is equal to 0.5 of the axial air flow velocity. The changes of the orifice radii, orifice area and number of orifice holes, do not appreciably affect the Cd variation with S.