The Science and Technology of Void Fraction Measurements in Multiphase Flow

Void fraction measuring techniques are reviewed with emphasis on applications to multiphase flow. The presentation is divided into two main sections; intrusive where the probe penetrates into the flow field, and non-intrusive where the detection is done remotely. The latter is more preferrable than the former. We subdivided the non-intrusive techniques into into two main categories; nuclear and non-nuclear. In the nuclear section, we discussed the utilization of almost all types of radiations, namely; beta, neutrons, gamma, X-ray, near infrared, in addition to the nuclear magnetic resonance. In the non-nuclear techniques, we presented the following methods; fluorescence, optical sensors, laser, autotransformer winding, ultrasonic, and photgraphy. Some other non nuclear miscellaneous techniques were discussed.