Volume fraction meter for multiphase fluid flow

A flow system comprising a volume fraction meter, a primary flow line, and a secondary flow line, and a volume fraction meter comprising a flow meter and a strain gauge, wherein:

• the secondary flow line is fluidly coupled to the primary flow line and comprises a nozzle opening and a turned portion that is upstream of the nozzle opening with respect to a flow direction;
• the flow meter is coupled to the secondary flow line upstream of the turned portion of the secondary flow line, with respect to the flow direction, and is configured to measure a volumetric flow rate of a multiphase fluid flowing in the flow direction through the flow line;
• and
• the strain gauge is coupled to the secondary flow line between the flow meter and the turned portion of the flow line, and is configured to measure a bending strain on the secondary flow line upon discharge of the multiphase fluid through the nozzle opening, such that the bending strain and the volumetric flow rate provide inputs for determining a mixture density of the multiphase fluid.

A method of determining a volume fraction of a liquid portion and a gas portion in a multiphase fluid, the method comprising:

• measuring a volumetric flow rate of a multiphase fluid flowing through a flow line in a flow direction using a flow meter coupled to the flow line, wherein the flow line comprises a turned portion, the flow meter is positioned upstream the turned portion with respect to the flow direction, and the flow line comprises a nozzle opening downstream the turned portion;
• measuring a bending strain on the flow line upon discharge of the multiphase fluid through the nozzle opening using a strain gauge coupled to the flow line between the flow meter and the turned portion;
• determining a mixture density of the multiphase fluid based on the volumetric flow rate and the bending strain;
• and
• determining a volume fraction of a liquid portion and a gas portion of the multiphase fluid based on the mixture density of the multiphase fluid.