Phase volume fraction measurement of slug flow with surfactant based on an image-quick closing valve method

The characteristics of gas–liquid two-phase flow with surfactant have been extensively investigated, and phase volume fraction measurements are commonly performed using the electrical conductivity and quick closing valve (QCV) methods. However, these methods have obvious deficiencies caused by the effects of foam formation. In this study, a phase volume fraction measuring scheme was proposed for slug flow with surfactant based on the image-QCV method. First, a QCV system and a high-speed camera system were triggered synchronously; the fluids were measured, and images were captured. Then, the level set method without re-initialization was employed for the image segmentation of the fluid characteristic structures. The volumes of the characteristic structures were evaluated via contour extraction, proportion calculation, and image correction. Eventually, the phase volume fraction was acquired using fluid distribution characteristics. The measuring results show that the liquid volume fraction of the liquid slug with surfactant decreases significantly compared to that for the air–liquid slug flow. With an increase in the superficial gas velocity and surfactant concentration, the gas volume fraction increases whereas the liquid volume fraction and foam quality decrease in the liquid slug with surfactant.