CFD Simulation of Flow Through the Orifice at the Inlet and Outlet Lines of the Thermal Diffusion Column

Orifices are simple devices without moving and electronic components that can be used in the enrichment industry and can be applied with a higher-pressure difference than control valves and it is very low-priced. The main goal of this research is the examination of different gas flow through an orifice and the determination of optimum conditions for the control application inside the inlet and outlet lines of the thermal diffusion column. Computational fluid dynamics was utilized to predict the behavior of gas flow through an orifice using COMSOL software. The three-dimensional orifice model with the compressible gas flow was applied in our model. To validate the model, the reliable and common correlations in this field, e.g., Singhal et al. and O’Hanlon were used. The results were presented in two sections: supersonic and subsonic flow. The result shows that in the supersonic flow, the temperature and velocity in the throat decrease sharply and the pressure drops. Also, in the subsonic flow at the throat, velocity increases, and accordingly pressure decreases. The results of the simulation of the supersonic and subsonic flow showed that the three-dimensional model can accurately predict the behavior of orifices.