The current energy transition effects the aviation industry heavily. To find sustainable propulsion systems, electric power systems are proposed and with that the interest in propellers has increased. The concept of ducted propellers can increase the efficiency of propeller systems. However, ducted propulsion systems are limited in operation by inflow conditions. High angles of attack can lead to separation on the inlet of a duct or nacelle, causing distortion on the propeller or fan. This thesis discusses the use of passive momentum addition on a ducted propeller to reduce the separation on the lower lip of the inlet. The simulation was performed on the ducted propeller design of the Bell X22. A hybrid CFD simulation was applied where the propeller is modelled by an actuator disk with an applied pressure jump. This pressure jump was derived from the low fidelity ducted propeller simulation program Ducted Fan Design Code (DFDC). With a half model of the duct the separation on the lower lip was investigated. The unsteady RANS solver from Ansys Fluent was used to solve for unsteady separated flow. Using tangential blowing on the lower lip the separation on the lower lip was postponed and the distortion on the propeller plane was reduced. With active momentum addition a prescribed momentum coefficient was applied on the blowing slot and the distortion factor DC60 could be reduced by 78% with a Cμ of 6%. To discuss the passive momentum addition, the pressure on a flush and ram port behind the propeller were measured. The measured pressure was applied to the blowing slot, with an additional loss factor. This loss factor was based on a channel flow equation, similar to the Darcy-Weisbach equation. The system with a ram port displayed significant reduction in distortion, a reduction of 50% in DC60 was possible. At higher thrust setting, the distortion was reduced by 63% with respect to the original duct design. Using a flush port, the distortion factor was not reduced, but increased by 23%, while at high thrust the increase is 9%. It was found that the flush port provided a low momentum coefficient, which was applied at the slot. In practice, this displaces the boundary layer with a lower momentum boundary layer. The boundary layer close to the surface has low momentum which cannot move through the adverse pressure gradient induced by the curvature of the duct. This induces separation, even though the system is intended to postpone separation. The results indicated the possible effectiveness of the passive tangential blowing system with a ram port, while a possible problem with the tangential blowing concept was identified for low momentum values. It was concluded that the system proposed in this thesis operates effectively if a ram port is utilised. Additionally, it was concluded that any system functioning on the concept of tangential blowing can also induce separation.