Research On Characteristics Of Variable Proportion Gas-liquid Two-Phase Flow Sampler

Phase distribution is a phenomenon that gas-liquid two-phase flow often encounters in the flow process.The equal dryness distribution is the best way to distribute the gas-liquid twophase flow,that is,to keep the proportion of the gas-liquid phase of the two-phase flow in the sample flow and the main flow path consistent.However,the phenomenon of phase separation occurs during the distribution of gas-liquid two-phase flow.So far,in order to solve the problem of phase distribution of gas-liquid two-phase flow,various sampling distributors and distribution structures have been designed,such as tee,header,sample tube distributor,drum distributor,swirl tube sampling distributor,rotary distributor and critical sampling distributor.The literature indicates that the current sampling ratio of the distributor will be difficult to change once the structure of the distributor has been determined.The sampling ratio cannot be coordinated according to the needs and changes in the upstream flow rate,and the adaptability is poor.Two variable-ratio gas-liquid two-phase flow sampling distributors,an axial narrow distribution regulator and a circumferential circular holes distribution regulator were developed.The main research contents of this paper are as follows:(1)The numerical simulation software FLUENT was used to optimize the structure of the swirling vane.The rectification effect of the swirling vane on the gas-liquid two-phase flow was also simulated.The phase distribution under the action of the swirling vane were obtained.The number of suitable swirling blade cycles is 4 or 5,and a uniform and stable annular flow can be formed at 50-70 mm behind the swirling blade.(2)Axial narrow slit distribution regulator which was characterized in arranging multiple sampling slits along the circumference was developed.Spiral vanes were mounted on the front side of the slit and the slit was divided into a front sampling split port and a rear main fluid split port by moving the baffle.The two ports were connected to the sampling fluid collection chamber and the main fluid collection chamber,respectively.The distribution effect of gasliquid two-phase flow through the distributor was simulated.The simulation and experimental results show that distribution characteristic of gas-liquid two phase flow is consistent in terms of the circumferential,but along the axial front sampling split port and rear main fluid split port serious phase separation phenomenon are occur.The pressure at the sampling split port side is higher than that at the main fluid split port,and the degree of phase separation is greatly affected by the gas-liquid flow rate and the theoretical split ratio and not affected by the inlet two-phase flow pattern.(3)In order to overcome the shortcomings of the axial narrow slit distributor regulator,an circumferential round holes distributor regulator was developed independently.The regulator arranged 20 split ports evenly along the circumference of the pipe.The diameter of the split holes is 2 mm and 3 mm,respectively,and swirl vanes were installed on the front side of the split holes.A fixed baffle plate and a rotating baffle plate were arranged outside the pipe,and the 20 distribution ports were respectively divided into a sampling fluid collection room and a main fluid collection room.Rotating the rotary baffle can change the number distribution of the distribution port in the two rooms.The distribution characteristics of the gas-liquid two-phase flow through the distribution structure were simulated.The simulation results show that the pressure,velocity and phase distribution at each outlet of the distributor are basically the same,and the distribution process is equal dryness distribution.The experimental results also shows that at the low gas-liquid phase velocity,the distribution process is unequal dryness distribution and the equal dryness distribution is at high gas-liquid phase velocity.At the same time,the experimental results can also obtain the working range of the two kinds of caliber distributors.The working range of the 3mm caliber distributor is higher than the working range of the 2mm caliber distributor.In the dry distribution process,it is not affected by the gas-liquid flow rate,the upstream flow pattern,and the position of the splitter.The circumferential holes distributor proposed in this paper ensures that all orifices have the same flow characteristics through flow pattern adjustment and holes splitting.The distribution ratio depends only on the ratio of sampling holes to the total number of holes and not effected by the inlet flow type or gas-liquid flow rate.And the regulator can be evenly distributed within the 0-100% split ratio which has a wide application prospects...