Скачать или смотреть Optimizing Turnbar Design for Web Handling: Excel-Based Fluid-Structure Interaction Simulation

This video showcases a complex Fluid Structure Interaction (FSI) problem in the web-based printing and roll-to-roll converter industry, where a flexible web must be guided contactlessly over a 180° turn-bar (air-turn, air-reverser) using an air cushion. Internally pressurized by a compressor, the turnbar expels air through small holes, building a controlled pressure layer that supports the web with minimal contact.

Initially, the video demonstrates surface pressure distribution around a standard circular turnbar, with a 15 kg tensioning weight. When air pressure is applied, the web lifts slightly, and airflow through the narrow slit between the web and turnbar creates regions of positive and negative static pressure. At the entry and exit points, negative pressure can cause the web to contact the bar, leading to ink buildup and web breaks—classic FSI issues. Achieving proper equilibrium requires the web's shape to align with the local pressure environment.

Through simulation, the turnbar design is progressively optimized. First, diffuser regions responsible for negative pressure are removed, eliminating problematic zones and reducing required compressor power from 1.55 kW (circular bar) to just 0.63 kW for the optimized bar. This adjustment narrows the cross-sectional airflow gap, greatly minimizing axial air losses.

In the final stage, the turnbar's cross-section is further refined: the curvature radius is proportionally increased with distance from the air exit holes, reaching infinity at the entry and exit. This results in a nearly constant 1 mm gap along the entire circumference, showcased in the last image. These changes lower compressor power demand even further to just 0.41 kW and reduce axial air losses to a minimum.

All simulations and optimizations were performed exclusively in Excel, demonstrating the power of spreadsheet modeling for solving advanced FSI challenges in web handling.

Keywords: Turn-bar; Air-turn; Air-reverser; Fluid Structure Interaction; Web Handling; #rolltoroll; Excel Simulation; Air Cushioning; Compressor Power Savings