Based on the two-equation k-ε turbulence model and four typical astronomical enclosures for the 2.5 m optical telescope, the numerical wind tunnel simulation is conducted by the computational fluid dynamics software Fluent. With the environment of different wind directions and same wind velocity, the distributions of the wind velocity and turbulence kinetic energy around the telescopes and the effects on astronomical observation when the enclosures are opened and pressure distributions on the enclosures when the enclosures are closed are obtained. The results show that when the enclosures are opened, the classical and calotte enclosures with better closure property have significant effects to prevent the telescopes from high-speed wind of different directions and cause low turbulence kinetic energy but high seeing around the telescopes, while the columnar and foldable enclosures with better openness make the wind velocity around the telescopes and the turbulence kinetic energy along the observation directions both much higher, but the seeing are both much lower. When the enclosures are closed, the surface pressure on the four enclosures all change from positive maximum to negative maximum and then approach zero along the wind direction. According to the analytical results, some applicable conditions and unfavorable factors of different astronomical enclosures are proposed, which provide a reference for the structural design of astronomical enclosures under different weather conditions in the future.