Method and system for determining flow rates and/or fluid density in single and multiple-phase flows utilizing discharge coefficient relationships

According to one embodiment of the invention, a computerized method for determining a flow rate of a fluid flowing through a conduit having an obstruction flow meter includes receiving a β ratio value indicative of a β ratio of the obstruction flow meter, receiving a pressure differential value indicative of a pressure differential across the obstruction flow meter, receiving a density value indicative of a density of the fluid, receiving a discharge coefficient formula for the obstruction flow meter, the discharge coefficient formula being a function of the β ratio of the obstruction flow meter and an Euler number for the fluid flowing through the conduit, and determining, by the computer, the flow rate based on the received β ratio value, the received pressure differential value, the received density value, and the received discharge coefficient formula. The determined flow rate may either be the volumetric flow rate or the mass flow rate. Alternatively, the density of the fluid may be determined by providing the flow rate of the fluid, the β ratio of the obstruction flow meter, the pressure differential value, and the discharge coefficient formula.U