The effects of dual‐orifice air‐ring design on blown film cooling

Abstract Numerical simulations of turbulent air flows tangentially impinging on blown film bubbles have been carried out. The cooling air is assumed to originate from a dualorifice adjustable air‐ring. The streamline patterns and heat fluxes are determined through a finite volume numerical technique for modeling of turbulent air flow. It is shown that cooling efficiency is critically sensitive to the air‐ring design as minor modifications cause large variations in cooling performance. Additionally, for a given design, the operational setup of the air ring is equally critical to the cooling performance. It is explained that the large influence observed on heat transfer rates is primarily due to the Coanda effect, which forces air jets to attach themselves to surfaces.