The Design Of Uniform Gas-solid Two-phase Flow Experimental Device And Simulation Studies

The numerical simulation of gas-solid two-phase flow is a common method for studying industrial production processes,and is widely used in fluidized bed,exhaust gas monitoring,and fine particle measurement.In practical applications,the setting of the boundary parameters and the adjustment of the physical model have a very large influence on the accuracy of the measurement results.Aiming at the problem of inaccurate particle measurement caused by environmental noise in gas-solid two-phase flow,a uniform gas-solid two-phase flow experimental device is designed in this paper.Through the simulation study of multi-particle particles,the ideal observation environment is explored for particle measurement.The main research contents are as follows:(1)Designing the system structure of the uniform gas-solid two-phase flow experimental device.The entire device system is composed of a particle generating device,an inlet pipe,a dispersion space container,an outlet pipe and the like in sequence.In the dispersion space,the orifice plate is the core assembly that promotes uniform distribution of the particles.On the basis of the Galton plate experiment,the orifice distribution of the traditional orifice plate was improved,and the orifice distribution design with sparse inner ring and dense outer ring was proposed,which effectively improved the diffusion effect of the particles.(2)Establishing a physical model of the scattered space container and realizing mesh division of the dispersed spatial watershed.For the difficulty of geometric geometry of the orifice plate and the incompatibility of the mesh quality with the mesh quality,a hybrid meshing structure method is adopted to reduce the number of meshes,and the mesh quality is improved by detection and mesh encryption.Among them,the orifice plate part adopts unstructured grids,and the other part adopts structured grids.(3)Using computational fluid dynamics and discrete element model(CFD-DEM)to simulate the particle diffusion process in the dispersion space,and proposing the uniformity quantification method of gas-solid two-phase flow.The set position of the observation window is determined by the relative diffusion degree(Q)of the particles in the vertical direction;a circular uniformity quantization algorithm is proposed in the horizontal direction,and the uniformity of the particle distribution is quantified by the coefficient of variation(cv).Through the simulation of a variety of different particle size particles,the optimal observation time domain is proposed and the rationality of the observation window position is verified.In this paper,the enhancement of the particle diffusion in the experimental space is carried out by simulating the motion state of the particles in the dispersed space,which provides a uniform measurement environment for particle detection.The experimental results show that the optimal observation time of 10 ?m particles is between 40 seconds and 70 seconds,and the coefficient of variation of the best observation point in the observation window is 0.92.The optimal observation time of 2.5 ?m particles is between 60 seconds and 140 seconds.The coefficient of variation for the best observation point is 0.95.The observation time of different particle size particles is different,the optimal observation area is very similar,and the observation window is suitable to be placed in the middle of the dispersion space.