Flow rates measurement in a gas-liquid mixture by means of phase density signals

Adiabatic two-phase flow in horizontal ducts of 60 mm i.d., 200 diameters long, flowing in plug and slug region, is investigated by means of 9500 phase density signals captured by local probes. An appropriate processing of phase density signal puts in evidence the well-known void fraction a and the flow complexity cf. According to considerations concerning the flow structure and the liquid phase kinetic energy, a correlation among a, cf, UL (UL being the liquid velocity) is expected and experimentally confirmed. A particular aspect of such correlation is the possibility of measuring the mean flow rates of each phase of the gas-liquid mixture. The analysis, carried out on data acquired in different experimental campaigns, confirms the validity of the present method, supplying a good evaluation of phases flow rates. Nevertheless such method is affected by a difficult and time-consuming experimental detection which prevents practical applications. To overcome this drawback, the cross section average values of a and cf are determined through few points vertically placed, properly weighting the experimental values. Such approach allows the continuous, real time, measurement of the flow rates of gas and liquid phases by means of a single multi-tip probe vertically placed in the duct.