Bubble detecting bubble has been a basic issue in two-phase flow systems. In this paper, a new method for measuring the frequency of bubble formation is presented. For this purpose, an electronic device is designed and constructed to work based on a change in intensity of the laser beam. Continues light beam is embedded just above the needle, which is received by a phototransistor. When bubbles go through the light beam, they make a deviation on it and change its intensity. So, the electrical resistance between two bases of phototransistor changes, and this variation is sensed by an electronic board. Based on the number of interruption and duration time, the frequency of bubble formation is be calculated. liquid and Gas phases in the present work are water and air, respectively. Tests are performed in constant liquid height (60 mm above the needle), constant needle diameter (1. 6 mm), and Gas flow rates between 50 to 1200 ml/hr. Also, three other methods are utilized to measure the bubble frequency: image processing (IP), numerical modeling, and theoretical model. Results show that with an increase in the flow rate of the Gas phase, the frequency of formation increases approximately in a linear manner. Validation of methods with IP method shows that the new device has very good accuracy for measuring bubble formation frequency. So because of the simplicity of using and low cost, it can be a superseded method of image processing.

This study aimed at linear stability analysis of the stratified two-phase liquid-Gas flow in a horizontal pipe. First, equations governing the linear stability of flow in each phase and boundary conditions were obtained. The governing equations were eigenvalue Orr Sommerfeld equations which are difficult and stiff problems to solve. After obtaining the velocity profiles of the Gas and liquid phases in the pipe, the instability equations for each phase with related boundary conditions were coupled and simultaneously solved by using the Chebyshev Tau-QZ polynomial method. The instability spectra for some points has been plotted and some curves about instability conditions the same as neutral stability curve which shown stable and unstable region respect to Reynolds number had been drown. According to the neutral stability curve for each phase, the liquid phase is more exposed to instability than the Gas phase. The liquid phase was unstable in low Reynolds numbers and a large amplitude of the wave velocity α but Gas was unstable in higher Reynolds number and small amplitude of α .

Measuring the volume of a bubble, especially at its detachment, is a basic subject in Gas-liquid two-phase flow research. A new indirect method for this measurement under constant flow conditions is presented. An electronic device is designed and constructed based on laser beam intensity. This device calculates the frequency of the bubble formation by measuring the total time of the formation process and counting the number of bubbles crossing the laser beam. The bubble volume at detachment can be calculated by dividing the volumetric flow rate of air by the frequency of bubble formation. The latter and the bubble volume at detachment are measured for three different heights of water above the tip of the orifice (50, 100, and 150 mm), three orifice diameters (1, 2, and 3 mm), and different Gas flow rates between 2000 and 10000 ml/hr. Comparing and validating the results with the results of the image processing (IP) method and the correlations presented by other studies shows the strong accuracy of the present method.

Existing liquid holdup models are generally based on low Gas and liquid velocities. In order to extend the applicable range of existing liquid holdup prediction models and improve its prediction accuracy, a of Gas-liquid two-phase flow experiment was carried out using a pipe of inner diameter 60mm and length of 11. 5m. The superficial Gas and liquid velocity ranges were 14. 07~56. 50m/s and 0. 205~1. 426m/s, respectively. The results indicate that the liquid holdup decreases with the increase of the superficial Gas velocity and increases with the increase of the superficial liquid velocity. A new annular flow model for calculating low liquid holdup in horizontal pipe was developed and presented considering the relationships between the friction factor ratio of liquid phase and Gas-liquid interface as well as the superficial Reynolds number of Gas and liquid. The predictions of the model are found to be accurate with an average absolute error of 4. 8%. Further, on the basis of the Beggs-Brill model and the horizontal pipe model established in this paper, a new liquid holdup model for different angles was given. It was observed the resultant model is also accurate, and has an average absolute error of 10%.

The mixing of oil and Gas forms the foundation of deep-sea oil and Gas extraction and transportation. However, traditional conveying equipment has low efficiency and high failure rates. In this study, a spiral axial flow Gas and liquid multiphase pump was used as the base model. The Eulerian multiphase flow model and RNG turbulence model were used for numerical simulations to analyze the internal flow field of the multiphase pump. A modification scheme was proposed to twist the airfoil shape and create a twisted vane. The twisted blade with the center of the hub-side flange chord length as the twisting center was twisted in the counterclockwise direction to help reduce the relative volume of Gas in the flow channel. When the twisted vane with the hub-side airfoil type trailing edge point as the twisting center was twisted in the suction side direction, it helped to accelerate the movement of the Gas-liquid mixture at the trailing edge of the back of the vane and further reduced the low velocity zone at the back of the vane. When the twist center is located at the hub side wing type trailing edge point of the twist vane, the twist degree is 0. 214. This results in the maximum head and efficiency of the pump, improves Gas phase aggregation phenomenon, and enhances the performance of the multiphase pump.