Measurements in two-phase flow

Measurement techniques for fully dispersed, two-phase flows of bubbles, drops or solid particles are discussed; in general, attention is limited to turbulent flows, though measuring systems applicable to both laminar and turbulent flows are also considered. Removal or mechanical measurement techniques involve trapping a sample, isokinetic sampling, inertial collecting (often on a treated microscopic glass slide), or collection after freezing. Probe measurements, which yield local concentration and sizing assessments, utilize impact probes, optical probes, microthermocouples, or hot wire/film anemometry. Photographic techniques, holograms, light scattering methods, laser Dopplers and interferometers are included in the category of optical methods. Bulk techniques, which provide measurements of void fractions in bubbly flows, include radiation attenuation methods and ultrasonic assessments.