Research On Flow Field Characteristics Of Gas-Liquid Cyclone Under Pressure Pulsation Conditions

In the process of oilfield exploitation,due to the instantaneous pressure pulsation of the pump,and the gas-liquid cyclone is directly connected to the pump,the pressure at the inlet of the gas-liquid cyclone changes periodically,and the internal flow field of the cyclone is disordered,resulting in a decrease in separation performance.In addition,the movement of gasliquid two-phase in the gas-liquid cyclone has an important influence on the separation performance.In order to solve the problem of separation performance reduction caused by pressure pulsation,this paper studies the flow field characteristics in the gas-liquid cyclone under pressure pulsation conditions,and analyzes the dynamic behavior of bubbles and the gasliquid two-phase flow pattern in the swirl field.It is of great significance to reveal the law of gas-liquid two-phase movement in the swirl field and guide the design of gas-liquid cyclone under pressure pulsation conditions.The numerical simulation method was used to explore the flow field characteristics of the gas-liquid cyclone under constant pressure and pressure pulsation conditions.The separation performance of the gas-liquid cyclone under pressure pulsation conditions was 7.2% lower than that under constant pressure conditions.At the same time,the influence of different void fraction and frequency on the flow field and separation performance of gas-liquid cyclone under pressure pulsation conditions was analyzed.When the gas content increases from 30% to 60%,the increase of air intake leads to the increase of the width of the inner gas core of the cyclone,the decrease of the wall pressure and the decrease of the average separation efficiency.When the frequency increases from 0.5Hz to 5Hz,the average separation efficiency of the gas-liquid cyclone increases first and then decreases.The population balance model was used to analyze the distribution of bubbles with different particle sizes in the gas-liquid cyclone under different operating parameters.The pressure pulsation condition improves the aggregation of bubbles with a particle size of 10.1mm at the axis,but at the same time increases the distribution range of bubbles with a particle size of 6.35 mm at the position of the underflow port,and the gas-carrying phenomenon of the underflow liquid phase is obvious.With the change of void fraction,the volume fraction of bubbles with 10.1 mm particle size increases and the distribution range is wider,thereby reducing the distribution range of bubbles with other particle sizes and reducing the volume fraction.The change of frequency has a great influence on the distribution of bubbles with particle size greater than 6.35 mm.The aggregation of bubbles increases first and then decreases with the increase of frequency.The visualization experiment of gas-liquid two-phase flow in gas-liquid cyclone was carried out by using high-speed camera system.Bubbles are susceptible to the intensity of turbulent flow field in the cone section,and the collision probability between bubbles increases,which is prone to coalescence and breakage.According to the migration law of bubbles in the swirl field under pulsating conditions,the gas-liquid two-phase flow pattern in the swirl field is divided.The separation performance of gas-liquid cyclone under different working conditions was analyzed by laboratory experiments.When the gas content increases from 30% to 60%,the separation efficiency decreases in the cycle.When the frequency increases from 0.5Hz to 5Hz,the average separation efficiency increases first and then decreases.