ESTIMATION OF VOID FRACTION AND PRESSURE-DROP FOR 2-PHASE FLOW IN FINE PASSAGES

The void fractions and frictional pressure drops occurring in two-phas e air/liquid flows in smooth-walled, circular-section ducts with diame ters from 0.74 to 3.07 mm have been measured for vertical and horizont al flows over a wide range of conditions: 0.05 < Re(L) < 4000; 15 < Re (G) < 12000. Existing correlations for frictional pressure drop genera lly perform satisfactorily for Re(L) > 1000 and it is concluded that f ine passage dimensions are do not of themselves present any problems t o these correlations under turbulent conditions. For Re(L) < 1000, a m odification of the Beattie correlation is recommended. Both the Lockha rt-Martinelli and the more complex CISE correlations for void fraction describe the measured void fractions satisfactorily over the whole ra nge of conditions studied.