Abstract: A solver is developed under the OpenFOAM open source framework. The solver is validated by simulating the dynamic equivalent lift coefficient of the rotary slotted cylindrical gust generator, which is in good agreement with the experimental result. The numerical simulation and flow field analysis are carried out for the downstream flow field disturbance velocity. The effects of the rotation direction, the rotation frequency, and the flow velocity on the downstream flow field are analyzed. The results show that, the rotation direction of the cylinder has different effects on the flow field of the upper and lower sides of the center line with greater interference near the center line. The change of gust amplitude is related to the reduction frequency, and the sinusoidal characteristics of the gust are best when the reduced frequency is 0.2~0.25. The results of this numerical simulation have some guiding significance for the design of the test device.