Numerical Simulation Study Of The Impinging Stream Inside The T-tube And Jets In Cross Flow Inside The Straight Pipe

Impinging stream and cross jet are two common types of flow.Because of their own advantages on the flow,heat and mass transfer as well as mixing,they are widely applied in industry.Based on their wide applications,both the impinging stream of gas inside the T-tube and gas-particle jets in cross flow inside the straight pipe were simulated by the lattice Boltzmann method and the lattice Boltzmann equation-discrete element coupled method respectively.Single-phase impinging stream is the basis to study the impinging stream.Hence,the incompressible thermal lattice Boltzmann model,namely the TD2G9 model,was adopted to obtain the velocity and temperature fields of the gas-phase impinging stream inside the T-tube.First,in this dissertation,the velocity field was validated by comparing our simulation results with the results from literatures.Meanwhile,a two-dimensional confined impinging jet simulation was conducted.The results are consistent with those in the literatures.Therefore,the reliability of the model can be validated further.Then,the influences of the Reynolds number,the ratio of pipe-diameter(the diameter ratio of the vertical pipe to the horizontal pipe)and the speed ratio of two inlets on the vortex structure,as well as velocity distribution and temperature distribution of the flow field were analyzed.Meanwhile,the relationships between the characteristics of heat transfer and mixing in the T-tube and several factors,including the Reynolds number,the ratio of pipe-diameter and the boundary condition of temperature,were summarized.For the gas-particle jets in cross flow,the TD2G9 model was employed to simulate the gas-phase.The Newton's motion equation was adopted to simulate the motion of particles.Meanwhile,the hard sphere model was adopted to simulate the collision of particles.A natural convection flow in a two-dimensional square was simulated.The reliability of this model was validated by comparing the results with those in the literatures.Then,four cases were simulated to study the effects of the particle size,the ratio of mass loading,the flow rate of particle numbers and the velocity ratio on the modifications of basic flow properties,velocities/fluctuations and particle dispersion characteristics.The results indicate that the increase of velocity ratio in the fourth case could improve both the mean flow and the turbulent kinetic energy simultaneously in the whole flow region.However,the other factors discussed in the former three cases have limited influences on the turbulent fluctuations or mean flows in local regions.