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 me asurements in adiabatic two-phase water-air flow in a small diameter t ube (9.53 mm, i.d.). Measurements were obtained on ground (vertical, u pward) and at microgravity conditions onboard NASA's KC-135 zero-gravi ty 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) w as applied to the temporal void fraction signals. It was found that th ere was a wider, fluctuation in void fraction values for the bubble an d slug flow regimes at 1 - g compared to mu - g. As the two-phase mixt ure inertia increased, the transitional and annular flows for 1 - g an d mu - g showed similar PDF distributions. (C) 1997 Elsevier Science L td.