An Investigation On Transportation Properties And Three-Dimensions Numerical Simulation Of Gas-Solid Injector

With the rapid development of combustion and gasification techniques under pressures in industry application, the technology of pneumatic conveying under pressures will be applied more and more widely. The gas-solid injector is a key devise in pneumatic conveying systems, its performance must be drawn attention. In this dissertation, a detailed investigation of several important parameters affecting the properties of gas-solid injector is performed in the practical application, experimental investigation and numerical simulation research.The test data such as static pressures, pressure drops and flow rates of gas within injector under various parameters are gathered by the computer real-time dynamic collecting system. It is found that the location of driving nozzle is the most important factor affecting the mass flow rate of solid. A reasonable position of driving nozzle helps to achieve the maximum material flow that also depends on other parameters such as backpressure, properties of conveyed material and driving gas. It is observed that, an increase of convergent section angle is harmful to the pneumatic conveying system, and also influences on the mass flow rate of conveyed material, the distribution of static pressures in injector and the pressure drops of conveying pipe. In addition, within a reasonable scope of air mass rate, increasing the driving jet velocity is more advantageous than enlarging the dimension of driving nozzle. However, if the driving jet velocity is too high the energy consumption of injector and conveying pipe will be raised and the pneumatic conveying system will be troubled. The backpressure of pneumatic conveying system is related to the driving jet velocity of gas-solid injector. The above-mentioned results are useful in design and application of the pneumatic conveying system.In this dissertation, the numerical simulation method of the solid phase field based on the Lagrangian description and the gas phase field based on the Eulerian description is first used in the numerical simulation research of the gas-solid injectors. A reasonable three-dimensions mathematical and physical model for two-phases flow in the gas-solid injector is developed, which not only takes into account the interaction between the particles and turbulence, but also considers the particle/particle collision. The PIV measurement technique and fast CCD photograph instrument are adopted in experiments. By compared testing data with computational results, it is found that the results of numerical solution are in satisfactory agreements with experimental data, which validates this model to be reasonable. The influences of the inlet tube angle, backpressure and driving jet velocity on static pressure distribution in the gas-solid injector are calculated, and the effects of the inlet tube angle on particle bulk phase concentration and axial mean speed of particles in the gas-solid injector are analyzed firstly. The predicament caused by lack of measuring means on the particle velocity in experiments is solved. All results of numerical solution in this dissertation showABSTRACTthat this model can provide a theoretical guidance for the design and improvement of the gas-solid injectors.