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

摘要

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 μ - 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 frcction values for the bubble and slug flow regimes at 1 — g compared to μ - g. As the two-phase mixture inertia increased, the transitional and annular flows for 1 - g and μ - g showed similar PDF distributions.