Slug flow measurement using a combined swirler and extended-throat Venturi device

A new method based on phase isolation for two-phase slug flow measurement is proposed in this study. A swirler installed upstream of an extended-throat Venturi (ETV) tube transforms slug flow into gas–liquid two-phase swirling flow. When the liquid superficial Reynolds number (Re_sl) is held constant, the two-phase multiplier for the radial pressure difference (φ_rl²) decreases with an increasing liquid–gas mass ratio (m_l/m_g). When either the liquid mass flow rate (m_l) or the gas mass flow rate (m_g) remains constant, the ratio K of the radial pressure difference of the gas–liquid two-phase swirling flow to the axial pressure difference in the front half of the throat section increases monotonically with an increasing m_l/m_g. By employing K to simplify the relationship of φ_rl² with Re_sl and m_l/m_g into an expression containing only m_l, and utilizing the monotonic relationship between m_l/m_g and K, measurement of the flow rates for each phase was achieved. Within the inlet gas superficial velocity range of 0.76–5.69 m/s, the liquid superficial velocity range of 1.02–1.87 m/s, and the gas volume fraction range of 29 %-85 %, for 95.18 % of the test points, the relative errors of m_l and m_g are respectively within ± 0.92 % and ± 9.89 %.