Velocity and Flow Rate Measurements in Capillaries With Arrays of Optical Fibres Available to Purchase

Results from the application of the spatial filtering velocimetry on capillary flow are presented. The type of the spatial filter is a differentail fibreoptical filter made by 16 step index fibres. Using tracer particles, the flow velocities along the capillary diameter and the volume flow were measured. The capillary is a transparent glass tube with inner diameter ranging from 0.15 mm to 0.5 mm. Using a gravitational measuring system the uncertainty of the flow measurement by the optical system was determined. For the laminar flow of newtonian fluids, the volume flow determination is based on the equation of Hagen-Poiseuille. The range of volume flow was 0.5 ml/h up to 50 ml/h.