Three-Dimensional Numerical Simulation Of Fluid-Particle Swirling Flow In A Straight Pipe

Swirling flow is one of the fashions which often appears in our everyday lives and nature. Swirling flow is a very complex flow because of the streamline curvature and the skewness of the velocity vector. It is a significant subject to study fruid-particle two phases swirling flow, and many study have been carried on it. With the development of computer, numerical method becomes an effective method to study fruid-particle two phases swirling flow. A Eulerian-Lagrange Model is applied in this dissertation to simulate fruid-particle two phases swirling flow in a pipe.Governing equations of a modified k - ε model is derived in a three-dimensional cylindrical polar coordinate system, and an available equation is produced. A discretization equation is derived by using a finite volume method in three-dimensional cylindrical polar coordinate system. Algebraic equations are solved by iteration with a line-by-line method that is a combination of TDMA in axial and radial directions, CTDMA in tangential direction and ADI method in three directions. The pressure and velocity coupling are solved with the SIMPLE algorithm. Relaxation factors are adopted. A program is produced to simulate swirling air flow in a horizontal straight pipe and compare with experiment data. The simulation prove that the modified k - ε model can predict the core, annular and wall regions near entrance and axial velocity far fromentrance, but it can't predict tangential velocity well in weak swirling area far from entrance. A simulation is carried on three swirling flow with different nonaxisymmetric tangential injection in a horizontal straight pipe to find if neglect their deflations whether they equate to axisymmetric module. A conclusion can be found that when nonaxiwymmetric conditions are occurred, there will be deflections near entrance that are different from axisymmetric condition, and these deflections will be erased on area far from entrance.The force and movement peculiarity of the particles in swirling flow is discussed and particles' equations are get on the basic of only counting on the flow field effect on particles. A program is produced to simulate the particle's tracks in swirling air flow in a horizontal straight pipe and find that the tendency of particle migration towards pipe center is not affected by initial position of a particle and all particles are sent into pipe by the axial motion of the swirling flow. The particles are rolled up by swirling flow. When the particle move to core area its tangential position change far.The Eulerian-Lagrange Model can predict particle tracks; it is an effective model to study fluid-particle swirling flows. The study in this dissertation has provided a good basis for numerical simulation of three-dimensional fluid-particle swirling flow in a pipe.