Tih < Sub > 2 < / Sub > In The Dispersion Of Aluminium Melt Numerical Simulation Research

Aluminum foams is a composite which made up of metal and pores, it can be used in many areas such as communication, construction, metallurgy, electronics, aviation etc. Distribution of foaming agent TiH2particles is the direct factor which influences the structure of pore and synthetic property of aluminum foams.In this paper, GAMBIT software was used to build stir pipe and vane models, mesh, set boundary conditions. Furthermore, the dispersion of TiH2particles in melt aluminum simulation study is also done by FLUENT6.3and multiple reference frame method; all the results are as below:(1) Flow field of melt aluminum is stable and TiH2particles distribute uniformly when stir velocity at45r/s-55r/s, however, low stir velocity (20r/s) can only accelerate melt aluminum at vane region, and TiH2particles will accumulate at the center of pipe. Vane is easy to idle and engender big eddy when stir velocity is too high (65r/s), and TiH2particles will concentrate at the outer boundary of the pipe.(2) Different cycle flow in the pipe is centralized at the bottom when one or two layers vane is used, however, three layers vanes can highly enhance the rotate speed of liquid surface and benefit to the cycle of all melt aluminum. In addition, the shape of vane also can influence TiH2particles’ istribution which reflected at the length and slant angle. Melt aluminum can only cycle by the center of pipe when the vane is too short, the velocity of outer melt aluminum in the pipe is very low and can not reach liquid surface. With the length of the vane increasing, when the ratio between diameter of pipe D and length of vane L at2:3, melt aluminum impact pipe wall and form uniform entire cycle; The vane can not engender pressure when no slant angle, only streamline flow formed. When the slant angle at θ=30°, the melt aluminum formed entire cycle along axis and radius, and TiH2particles distribute uniformly.(3) Temperature of melt aluminum can influence the dispersion of TiH2particles,978K is ensured as the best temperature. Melt aluminum has bad fluidity when temperature of melt aluminum is low because of the pressure engendered by vane preventing it flow back to up and TiH2particles are agglomerating at the bottom of pipe. Fluidity can be improved significantly with temperature increasing, and the velocity field of melt aluminum distributes uniformly, no palpable Ti2particles concentration difference exists in the pipe.(4) Concentration distribution of TiH2particles is related to stirring time. Melt aluminum is accelerated under the impact of vane, TiH2particles disperse to the whole pipe, The concentration difference reach to the minimum when time at65s, and there is no obvious changing with continuous stirring.(5) Velocity field of melt aluminum in the pipe is not variation with the percentage of TiH2particles, and concentration difference of TiH2particles is also no obvious variation.(6) We can obtain the conclusions according to simulation:stir velocity,quantity, length and slant angle of vane and temperature of melt aluminum are the main factors which influenced the distribution of TiH2particles, optimization and matching among those factors is the key factor to produce good quality aluminum foams.