Dynamic Gauging in Duct Flows

Dynamic gauging is demonstrated experimentally to work well in duct flows, thereby being suitable for monitoring the development of soft films in flowing systems, as illustrated using the growth of a freezing fouling layer viz. an ice film. For low duct velocities (440 < ReD < ca. 2000) we identify an undesirable multiple steady state phenomenon and show how to eliminate it. Dynamic gauging then proves useful up to ReD = ca. 10 000. Above that, we infer that the throat of the gauge nozzle would no longer be within the viscous sublayer and recommend further investigation of this regime.