Design and Testing of Instrumentation for Multi-Phase Flow Sampling and Local Void Fraction Measurement

Instrumentation is available to obtain samples and then measure the local void fraction as well as the size and number density of bubbles and/or particles in two and three-phase flow. But in most cases, these methods interfere with the flow and bias the sampling process. We have developed an isokinetic probe that can take accurate samples without changing the sample’s composites. This is achieved by aligning the probe’s intake nozzle with the flow’s local predominant direction and matching its internal pressure with its hydrodynamic environment and hence equalizing the inside and outside velocities. Then the fluid sample’s density is measured to calculate the local void fraction. The calibration procedure and results as well as extensive test data obtained in bubbly-flow tunnel and flotation cells respectively are presented and discussed.