  Dual-tip phase-detection probes can be used to measure flow properties in
gas-liquid flows. Traditionally, time-averaged interfacial velocities have been
obtained through cross-correlation analysis of long time-series of phase
fraction signals. Using small groups of detected particles, a recently
developed adaptive window cross-correlation (AWCC) technique enables the
computation of pseudo-instantaneous interfacial velocities and turbulence
quantities in highly aerated flows, albeit subject to some smoothing which is
due to the use of a finite window duration. This manuscript provides guidance
on the selection of optimum processing parameters for the AWCC technique,
additionally addressing shortcomings such as velocity bias correction in
turbulent flows and extrapolation of turbulence levels to single particles. The
presented technique was tested for three highly turbulent air-water flows:
smooth and rough-wall boundary layers (tunnel chute and stepped spillway), as
well as breaking shear layer flows of a hydraulic jump. Robust estimations of
mean velocities and velocity fluctuations were obtained for all flow
situations, either using dual-tip conductivity or fiber optical probe data. The
computation of integral time scales and velocity spectra is currently limited
by the data rate and must be treated with caution.
