The ‘Minituft’ surface flow visualisation method; experience of use in the RAE 5m pressurised low-speed wind tunnel

Abstract

SummaryThe development and use of a ‘minituft’ surface flow visualisation technique in the RAE 5m Pressurised Low-Speed Wind Tunnel is described.The method, due to Crowder, uses very fine nylon monofilaments to show surface flow direction. These tufts are made visible by coating them in a fluorescent dye and then illuminating them with a powerful ultra-violet light source.Because of their small size, a large number of tufts may be used without interfering with the flow to a great extent. However, it is shown that if accurate force measurements are required, then it is advisable to test the model in the absence of tufts.