Kj. Elkow et Ks. Rezkallah, VOID FRACTION MEASUREMENTS IN GAS-LIQUID FLOWS USING CAPACITANCE SENSORS, Measurement science & technology, 7(8), 1996, pp. 1153-1163
Void fraction measurements for vertical flow in a small diameter tube
(9.53 mm) were taken using two non-intrusive capacitive void fraction
sensors. The sensors were needed to measure the void fraction of water
-air two-phase flow under normal gravity and microgravity conditions.
Void fraction data were collected with: (1) a sensor having helical wo
und electrodes that was used to collect data under normal gravity and
microgravity conditions, (2) a sensor having concave plate electrodes,
used to collect data at normal gravity. This paper covers the calibra
tion results for both sensors and some of the problems associated with
the helical wound design. Nonlinearity in the helical sensor is addre
ssed, with improvements shown in the concave plate sensor. Comparisons
are made between the capacitive sensors, quick-closing valves and a g
amma densitometer.