Three-dimensional Measurement And Flow Characteristics Analysis Of Annular Liquid Film Based On Scanning-LIF

The gas-liquid flow is widely used in energy,environmental protection,chemical production,biological manufacturing and other industrial fields,which has an extremely important impact on human production and life.The annular flow is a common flow pattern of the gas-liquid flow,which often occurs in the process of oil and gas storage and transportation,evaporation and condensation.Measuring the characteristics of the annular flow liquid film accurately is of great significance for monitoring flow conditions,determining heat and mass transfer characteristics,ensuring production safety and improving production efficiency.The gas-liquid interface of the annular liquid film is distorted by the complex interface waves and has three-dimensional flow structure and characteristics.Therefore,it is very difficult to measure the liquid film accurately.In order to obtain the flow information of the liquid film as completely as possible,it is necessary to further develop the three-dimensional measurement technology to analyzed the liquid film.In this paper,the scanning laser-induced fluorescence(SLIF)measurement system of the annular flow was designed based on the planar laser-induced fluorescence technology and the laser scanning technology.On this basis,the fluorescence slice images of the flow field were collected,and the three-dimensional thickness distribution of the liquid film was measured.According to the features of the liquid film slice images,the flow parameters of liquid film were extracted and the three-dimensional flow structure of liquid film is reconstructed by the optimized image processing algorithm.The specific work includes the following:1.The existing three-dimensional laser measurement technologies were deeply analyzed.And the scanning laser-induced fluorescence measurement system of annular flow liquid film was proposed.The basic framework of the measurement system is designed.According to the flow characteristics of the liquid film,the galvanometer with high precision and good stability is used as the scanning device.And the complete scanning laser-induced fluorescence measurement system was constructed to obtain the sequential fluorescence slice images of the flow field.2.The imaging model of the high-speed camera in the SLIF system was analyzed and it was calibrated by the dot array calibration board based on Zhang calibration method.According to the calibration results,the poses of the fluorescent slice images were determined and corrected based on the PNP algorithm,and the flow information in the images was extracted.Based on the characteristics of the scanning system and liquid film,the slice images were interpolated and optimized.And the three-dimensional flow structure of liquid film was reconstructed to realize the three-dimensional visual measurement of the liquid film.3.The liquid film generating device was built and the liquid film was measured.And the three-dimensional flow structure of the liquid film was initially studied.The thickness distribution,fluctuation characteristics of the liquid film and the three-dimensional flow characteristics of the disturbance waves were extracted and analyzed.