CFD simulation and optimization of the capillary throttling of air-flotation unit

With respect to orifice throttling or compensating, capillary throttling has following advantages: smaller mass flow rate and stronger anti-interference ability. This paper firstly gives the required average pressure of air-film when shipping a piece of LCD glass. Then, dimensional flow model of the capillary throttling of air-flotation unit is established. Based on the model, we firstly analyze the flowing process of the lubricated air through the capillary. Secondly, the pressure distribution equation of air-film is derived from the Navier-Stokes Equation. Furthermore, the approximate functional relations between model parameters and static characteristics of the air-film, such as mass flow rate, static bearing capacity, are obtained and then influence of the former on the latter is analyzed. Finally, according to the continuity of air flow, the function relation between model parameters and pressure of core nodes in the air-film is also derived. On foundation of theoretical analysis, the impacts of each model parameter on static characteristics of the air-film flow field, are respectively simulated and analyzed by CFD software Fluent. Based on these simulations and analysis, radius and length of the capillary, density of the gas supply orifices and other model parameters are optimized. Finally, the best unit model is acquired, which greatly improves the static working performance of air-film in air-flotation unit. Research results of this paper can provide guidance and basis for the design and optimization of air-flotation transporting system.