Abstract
The proposed research is about analyzing and identifying different types of upward air-water two-phase flow regimes in the vertical pipe by measuring its pressure signal, differential pressure signal, and electric impedance signal. In addition, our research provides an observation section which is available for photographing and recording for data comparison. Currently, there is lack of a complete method for observing the signal; therefore, we create large database for analyzing the characteristic of each flow regimes. We want to have a unified and objective method to identify two-phase flow regimes in the future. This experiment provides photos, videos, pressure signal analysis, and void fraction analysis for each flow regimes. Especially, we provide a detailed analysis on wispy annular flow. Wispy annular flow was first observed by A.W Bennett. This regime will form irregular wisp structure within the gas core and this characteristic has unique physical significance. The experimental result shows that when wisp is formed, the pressure signal will have an instantaneous pulse. The instantaneous pulse is an important indication for wispy annular flow. We use signal processing methods for calculating correlation functions for pressure signal and conductivity signal. Therefore, we can get experimental results for the velocity, frequency of appearance, time duration of appearance, average pressure, pressure standard deviation, and the ratio of average pressure and total pressure of wisp. The experimental results of wisp given above would rise with the increase of superficial liquid velocity and change apparently when it reaches to a certain condition. However, the experimental results reveal that the characteristic of wisp is less dependent of superficial gas velocity. In this study, we set up an experiment device which was carried out to investigate the flow characteristics of wispy annular flow. The large database we build is important for the flow regime identification and characteristic analysis about wispy annular two-phase flow.