Air rings, used today in film blowing systems, have been developed down the years through trial and error experiment. They represent the limiting factor concerning the efficiency of film blowing lines with respect to throughput and take-off speed. Numerical simulation of the cooling and optimization of future cooling systems. Individual process and geometric parameters can be changed interactively with the effects on flow and heat transfer processes being analysed and applied to similar situations. The knowledge acquired regarding the physical interactions in the cooling of blown film makes a targeted optimization possible. The purpose of this paper is to present the foundamentals for calculating turbulent air flows in blown film extrusion and, additionally, a model for complete FE-simulation of the flow and heat transfer processes. Furthermore, the achieved simulation results will be discussed.