冶金法制备太阳能级多晶硅工艺技术研究

Numerical Analysis on the Effect of Squish Flow on the Combustion Process of a Gasoline Engine

以纯度99%的工业硅为原料,通过造渣熔炼、电子束炉真空熔炼和定向凝固手段进行了太阳能级多晶硅制备的研究。结果表明通过造渣熔炼、电子束炉熔炼、两次定向凝固的工艺成功地将工业硅中的总杂质含量（质量分数）降到了1 ppm以下,其中B低于0.3 ppm、P低于0.5 ppm、总金属杂质含量TM低于0.2 ppm、C浓度低于5×1016atoms/cm3、O浓度低于1.0×1017atoms/cm3,产品达到太阳能级多晶硅标准。与国内外已公布的冶金法制备太阳能级多晶硅工艺流程相比,本工艺未采用酸洗,清洁高效,没有任何污染。

In order to study the effect of squish flow on combustion characteristic in a PFI gasoline engine, the combustion processes of three combustion chambers with different piston crowns are numerically studied using the three-dimensional CFD software AVL-FIRE. The effects of squish area and squish clearance on flow velocity field, concentration field, turbulent kinetic energy field and combustion characteristic parameters such as heat release rate, mean pressure and combustion duration are researched. Results indicate that for the combustion chamber with reasonable designed piston crown, the squish flow is formed in the vicinity of TDC, which is helpful to the enhancement of combustion. Squish flow has a great influence on organizing the air motion in cylinder, increasing the turbulence intensity around the spark plug at ignition timing and improving the combustion process.