Low noise emissions of vehicle components are today a quality feature in the automotive sector. In automatic transmissions in particular, the hydraulic pump often contributes significantly to noise, which motivates research to clarify the noise sources and transmission pathways in these components. The subject of the present investigation is the generation of noise by the inherently instationary flow in hydraulic pumps. In order to shed some light on these phenomena, a computational fluid dynamics (CFD) simulation model for flow investigations on rotary vane pumps was set up. In this work, first the influence of different simulation parameters on the numerical results is analyzed. Then the pressure in the internal displacement chambers of the pump is examined, as it can be assumed that this is the essential parameter for noise generation. Different operating conditions such as rotational speeds and delivery pressures are investigated. Furthermore, the simulation results are compared to pressure measurements for validation and are used to find optimization potentials.