Our customer is a Food Industry Equipment Manufacturer involved in development and manufacturing of Food Processing products. Our customer product domain also covers frozen food processing unit. Such units generally encounter frost accumulation on conveyor belt. To reduce this occurrence, Air Knife is used. An air knife is a tool used to blow off liquid or debris from products as they travel on conveyors by high intensity laminar air flow. The Industry required us to optimize the design of the Air Knife for better performance.
By empirical relations, Air Knife geometrical model was formed for given flow rate and desired jet velocity. Jet velocity increases with decrease in nozzle gap but it also increases frictional pressure drop. So a optimal nozzle gap has to be obtained which gives highest possible jet velocity. A series of CFD simulation was conducted on the geometrical model preceded by 2D simulation to estimate jet dissipation and head loss factor. Simulation was carried out on two different tip designs- Square Tip and Pointed Tip. From the Centre-line velocity decay study it was found pointed tip design to be more efficient.
Based on the result, necessary design changes were made. The pressure drop across the width of the pipe was decreased by adding a blockage of calculated length. To allow the flow to be fully developed exit profile of nozzle was defined. Finally; we were able to deliver an optimized air knife design to meet their requirements.