Statistical analysis of void fluctuations in gas-liquid flows under 1-g and mu-g conditions using a capacitance sensor

A helical wound capacitance sensor was used to obtain void fraction measurements in adiabatic two-phase water-air flow in a small diameter tube (9.53 mm, i.d.). Measurements were obtained on ground (vertical, upward) and at microgravity conditions onboard NASA's KC-135 zero-gravity aircraft. Comparisons were made between the void fraction values by matching the flow rates obtained at both 1 - g and mu - g conditions. A statistical analysis using the Probability Density Function (PDF) was applied to the temporal void fraction signals. It was found that there was a wider, fluctuation in void fraction values for the bubble and slug flow regimes at 1 - g compared to mu - g. As the two-phase mixture inertia increased, the transitional and annular flows for 1 - g and mu - g showed similar PDF distributions. (C) 1997 Elsevier Science Ltd.