双螺杆食品挤压流动过程数值模拟

Numerical Simulation of Flow Process in Twin-screw Food Extruder

采用有限单元法对双螺杆食品挤压熔体的流动过程进行数值模拟。结果表明:物料熔体在流道内沿两螺旋槽环绕前进,整个过程长螺杆始终保持优先,啮合区剪切应力使物料熔体在两螺杆之间分流进而充分混合,最终转移至长螺杆后进入模具过渡段,该段熔体在螺杆头的转动影响下螺旋攀升,会形成涡流导致物料熔体滞留,是可能引起焦糊的原因。

The flow of food material in twin-screw extruder was simulated by the finite element method. The results showed that： Melt material flows forward along two helical grooves,anld material around longer screw is always in front. Material is diverted under shear force in the mating area, which makes the material fully mixed. After transferred from the end of short screw to long screw, material flows into the mold transition zone. Melt materials spiral and form a vortex, which may cause the retention.It is possible cause of scorching phenomenon.