Scope and Applicability This Item provides methods for calculating two-phase pressure losses for sudden expansions@ sudden contractions@ orifice plates@ valves and bends. The methods are based on the following assumptions: (i) the gas phase is incompressible@ (ii) phase velocities are well below sonic (critical)@ (iii) there is no mass transfer between the phases@ and (iv) there is no interaction between adjacent fittings. The data given in this Item are taken from isolated fittings where the flow is fully developed both upstream and downstream of the fitting. Flow disturbances upstream can either increase or decrease the pressure loss in a fitting depending on the fluid properties and flow regime. Measurements taken too close to a fitting can give a considerably larger pressure loss than would be obtained by assuming fully-developed flow (see Sketch 2.1).
ESDU 89012-1989 history
1989ESDU 89012-1989 TWO-PHASE FLOW PRESSURE LOSSES IN PIPELINE FITTINGS