Visualization of Flash Evaporation Process in Tiny Tube Based on Electrical Capacitance Tomography

Flash spray has been widely used in internal combustion engines, liquefied gas propulsion, skin laser surgery cooling protection, and other fields. In order to effectively control the spraying process, it is necessary to detect the flash evaporation in the tiny tube of the spraying device. But the existing detection methods are difficult to apply online or measure two-phase flow parameters such as liquid holdup. The flash evaporation process in the tiny tube is also a special case of gas-liquid two-phase flow. Therefore, in this paper, a 6-electrode electrical capacitance tomography sensor which is a visualized and suitable for multiphase flow monitoring is designed to realize the on-line measurement of the flash evaporation process. A non-iterative interpolation-based algorithm incorporating characteristics of flash evaporation is proposed to address the poor quality of reconstructed images by the 6-electrode sensor. Eight typical flow patterns which are established by numerical simulation are used to verify the algorithm effect. Reconstructed image and comparison of image error and correlation coefficient demonstrate its superiority over other typical non-iterative algorithms. And the experiment on the lab-built platform to generate flash evaporation prove that the designed sensor and the proposed algorithm can effectively visualize the flash evaporation process in the tiny tube online.