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What is the flow measurement of multiphase fluids?

What is the flow measurement of a multiphase fluid? The so-called "phase" is the state of what is commonly called a substance. Each substance can have three different physical states at different temperatures, namely solid, liquid and gaseous, which means that any substance has three phases, namely solid phase, liquid phase and gas phase. Multiphase flow is not a single phase material in fluid flow, but a motion in which two or more different phases of material exist simultaneously. Therefore, the two-phase flow may be a flow of a liquid phase and a gas phase, a flow of a liquid phase and a solid phase, or a flow of a krypton phase and a gas phase. There are also flows of gas-phase, liquid-phase, and solid-phase three-phase mixtures. For example, the gas ejected from a gas well is mainly natural gas, but it also contains a certain amount of liquid and sediment, which is a more complicated flow than the two-phase flow.

The various liquids are mixed together and sometimes become a well-mixed fluid, such as a mixture of water and alcohol, while others cannot, such as a mixture of water and mercury, the latter mixture having a similar property to the two-phase flow. When various gases are mixed, they can be uniformly mixed to become a single-phase gas. Therefore, the mixed flow of various gases is a single-phase flow.
The two-phase flow rate can be divided into two types, one is the two-phase mixture flow rate, that is, the total flow rate of the two-phase flow, and the other is the flow rate of each phase, and the sum of the flow rates of the respective phases is equal to the flow rate of the two-phase mixture.

To determine the flow rate of each phase, it is necessary to determine not only the flow rate of the two-phase mixture, but also the content of any of the two phases in the mixture. Taking the gas-liquid two-phase flow as an example, to determine the mass flow rate of the gas phase and the liquid phase, it is necessary to determine the mass flow rate of the gas-liquid mixture and the flow mass content pGm of the gas phase. The flow mass content of the gas phase, by definition, is equal to the ratio of the gas phase mass flow rate qc to the mass flow rate qm of the gas-liquid mixture. Therefore qG is equal to the product of qm and pGm, and the liquid phase mass flow qL is equal to the difference between qm and qc. Therefore, to complete the measurement of the gas-liquid two-phase flow, it is generally necessary to determine two parameters, namely the gas-liquid mixture flow rate ‰ and the gas phase mass flow rate pGm.

Some flowmeters, such as electromagnetic flowmeters and ultrasonic flowmeters, have output signals that are only volumetric flows. When used to measure two-phase flow, for various reasons, density measuring instruments are not installed. If the density of light and heavy phases is known, Flow volume ratio, the average density of the mixture can be calculated using the formula to calculate the mass flow of the mixture and each phase.

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