Upper Limit of the Gas Fraction in PIV Measurements in Dispersed Gas-Liquid Flows

In the chemical process industry bubble columns are widely used and there is a lot of interest in the modelling of the gas-liquid flow in such equipment with the aid of Computational Fluid Dynamics (CFD). In order to validate CFD simulations of gas-liquid flows in bubble columns one needs detailed measurement data at moderate gas fractions (i.e. up to 5 vol.%). For the validation of CFD results, one is typically interested in whole field information of the mean and fluctuating velocities of both phases. Particle Image Velocimetry (PIV) is a technique that can offer this data. The components of a PIV set-up are shown in Fig. 1.