Deposition of SiO2 Nanoparticles Produced in a Turbulent H2/O2 Flame

摘要

Measurements and simulations of an industrial outside vapor deposition process as used for the manufacture of optical wave guides were performed.Deposition efficiencies,flame temperatures,and gas velocities were measured.The hydrogen flame reaction was modeled by calculating the turbulent flow including a combustion model and using a computational fluid dynamics(CFD)solver to compute flow velocities,turbulence and temperatures in the flame.These results were compared with experimental data and reasonable agreement was found.The produced SiO2 particles with predefined size were tracked through the flow field and it was determined whether they hit the surface of the cylindrical target or pass it.Three flame configurations were investigated and the model could predict well the trends of the deposition efficiencies for the different flames.The differences in flame velocities and turbulence levels for the different configurations assisted the explanation of the performances of the flames.Turbulence levels were different for the three flames and it was concluded that for turbulent deposition processes the thermophoretic force that drives particles towards colder surfaces is less important than for laminar deposition processes.