Papers by Keyword: Number Simulation

Abstract: The deposition behavior of Al-Si particle on magnesium alloy by supersonic particles deposition was investigated by numerical stimulation. The results demonstrated that critical velocity of sprayed particle reduced as its initial temperature increased; Temperature at interface increased rapidly and reached to the value higher than melting point of Al-Si particle and ZM5 magnesium substrate, which predicts the melting possibility for collision interface. Morphology and microstructure of Al-Si coating on magnesium alloy were analyzed by SEM and TEM. The results indicated that there existed large amount of nano/micro-scale grains produced by sputtering and impacting of the melting Al-Si jet. And obvious interface belt had been formed at brim of the deposited particles, nanocrystalline phase region generated by rapid solidification of melting Al-Si particles, justified the occurrence of interface melting phenomena.

Abstract: In this paper, the biological droplet transport and deposition in the turbulent airflow inside an indoor environment was studied using the Lagrangian computational method. Meanwhile, as to the mathematic simulation, the Monte Carlo modeling method was coupled into this simulation program to describe the bio-particle transport. Many influent factors such as indoor airflow velocity, the bio-aerosol generator velocity, particle diameter, and evaporation and death were considered synthetically in this paper. Serratia marcescens was used as tracer microorganism to simulate the droplet nuclei exhaled by patients, and the spatial distribution of its concentration was measured. Collected bacteria were quantified using standard cultivating assays. It showed the simulation results were comparable with the data of the experimental findings.

Abstract: The simulation of the gas-solid two phase flow inside the abrasive jet nozzle is studied by the computed dynamic software (CFD)-FLUENT, the velocity field of the two phase flow and the trajectory of the abrasive inside the nozzle are obtained. The Eulerian multiphase model and the DPM model have been used to compute the two-phase flow field. The simulation results express that the velocity of the jet is slow at the inlet, while it will be increased with the area of the section decreasing, the cone angle of the nozzle affects the flow field very much, the flow has low turbulence and the gradient of the velocity is small when the cone angle is small, while the velocity of the flow increased rapidly and the gradient of the velocity is big when the cone angle increasing. The simulation results also express that the arc radius affects the flow field greatly, the flow will move more smoothly when the arc radius is large. The pressure field of the wall expresses that the nozzle will wear rapidly at the corner of the nozzle, the reason is that the pressure is big or changed greatly, the fatigue wear and the blast wear will happen at those place.

Abstract: Supersonic fine particles bombarding (SFPB) is an important way to perform surface nanocrystallization. Harder the material is, higher the bombarding particles speed is needed. The gun with excellent features is premise to obtain the nano-structured layer.This paper analysed the advantages of rectangle Laval nozzle compared to annular-shape one and calculated critical structured parameters of the nozzle.Numerical simulation analysis of flow field of the nozzle at inlet temperature 300K and inlet pressure 0.25 MP, 1.0 MP, 1.7 MP and 2.5MP and velocity field of the gun with divergent-angle extended-barrel conduced by a commercial finite volume code FLUENT software of CFD; Consequently, the overall structure of the gun was optimized and determined finally. The sample of 38CrSi steel was treated by this gun. And the nano-structure layer on the surface was observed by TEM.