Annular flow local dynamic liquid film average thickness direct measurement method

Abstract

The invention relates to an annular flow local dynamic liquid film average thickness direct measurement method, which is used for measuring the thickness of a liquid film of conductive liquid flowing in a pipeline. A data measurement module comprises a DC stabilized voltage supply, an insertion-depth-adjustable contact probe sensor and a precision resistor. The insertion-depth-adjustable contact probe sensor comprises a micrometer caliper 6, double parallel contact probes 2, a connecting piece 9, a fixation support 3, a telescopic support 7 and a spring 9. The direct measurement method comprises the following steps: when the conductive liquid submerges the lower ends of probes, the two probes are conducted and the whole circuit forms a loop, the current flows through the precision resistor, and the voltage at the two ends of the precision resistor is not zero; when no liquid exists between the two probes, the voltage at the two ends of the precision resistor is zero; and during continuous measurement, different duty ratios are obtained, and voltage signals corresponding to corresponding insertion depths are obtained; and finally, the average thickness of the local dynamic liquid film is calculated through the data processing module.

Description

technical field [0001] The invention relates to a method for measuring the average thickness of a local dynamic liquid film in an annular flow. Background technique [0002] Multiphase flow processes widely exist in many departments and industrial processes such as petroleum, chemical industry, metallurgy, water supply, medicine, and environmental engineering. It is an important research field that is widely concerned at home and abroad. A multiphase flow system usually consists of two continuous media and several discontinuous media. Different multiphase flows including the number of material phases in root excavation fluids can generally be divided into two-phase and three-phase flows. According to the different physical states of the components, two-phase flow is generally divided into gas / liquid, gas / solid, liquid / solid, liquid / liquid (such as oil / water) two-phase flow; three-phase flow is generally divided into gas / liquid / Liquid, gas / liquid / solid three-phase flow, et...

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Problems solved by technology

The optical method is one of the methods with high measurement accuracy. Among them, the interface detection method, laser scattering method and fluorescence intensity method generally need to add dyes, latex particles or fluorescent agents in the liquid phase. The accuracy of the added mass concentration, The change of excitation light intensity and time and space are directly related to the measurement uncertainty of liquid film thickness, its uniformity in the liquid phase cannot be guaranteed, and it is a consumable item, which is only suitable for laboratory measurement, which limits its popularization and application; The light and shadow method measures the thickness of the liquid film by recording the shadow formed by the reflection and refraction of the liquid film by the camera. This method has poor real-time performance and cannot respond quickly to changes in the liquid film; the laser focus displacement method and interferometry are very effective for measuring the thickness of thin liquid films. , high resolution, but the structure of the two measurement systems is complex and requires high sensor performance. Due to the use of transparent pipes, its use in the measurement of medium and high pressure liquid film thickness is limited; among the light attenuation methods, the visible light attenuation method is only suitable for For translucent media that absorb visible light, the mid-infrared attenuation method is only suitable for the measurement of extremely thin liquid films of 2-30 μm due to its strong absorption

Acoustic method is based on ultrasonic technology, which has a powerful function of describing flow pattern characteristics. It uses the principle of attenuation and reflection when passing through discontinuous media to measure the thickness of liquid film, but it cannot measure wavy liquid film, which will cause ultrasonic detection after reflection. difficulty

The disadvantage of the nuclear radiation method is that it is highly radioactive and requires heavy safety protection when used, which limits its application in industrial sites

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