An automated image analysing routine for estimation of equivalent diameter in high-speed image sequences with high accuracy and its validation

摘要: Abstract Bubbly flow plays an important role in industrial processes. Obtaining detailed information on the is, however, a challenging task. One of key process parameters is diameter bubbles, which often determined as equivalent diameter. In this study, automatic image analysis routine for time-resolved and estimation rising single bubbles high-speed sequences with high accuracy developed using open source software KNIME. Common techniques diameter, e.g. based major/minor axes, are compared to novel rotation algorithm, where detected bubble segments rotated by 180° 1° steps, determination Feret Additionally, elongation measured morphological parameter centroid positions determined. combination frame rate ascent rates can be calculated form Bubble Tracking Velocimetry (BTV). The was validated static computer generated geometrical shapes well precision grade solid glass spheres diameters 0.7–2.5 mm under dynamic (settling) conditions. High-speed were recorded analysed critical statistical evaluation. It could shown that deviation between real less than 1.5% when rotating algorithm. Settling velocities maximum error 3%. A first test analysing bubbly showed it unaffected dirt, small tracer particles or internals viewing area, makes combined Particle Image (PIV) Shadowgraphy feasible.