The Effect of Coefficient of Restitution in Modeling of Sand Granular Flow for Core Making: Part II Laboratory and Industrial Test

Abstract

Listen

Translate article

In this second part of the two-part article, a laboratory-scale core box, which is originally designed and built with a center wedge and slotted base, is adopted to validate the correlation tested in Part I between coefficient of restitution (COR) and flow performance of granular sand materials on a laboratory core shooter. A series of experiment is conducted as parametric study on the collision effect and fluid behavior by blown granular material of sand and resin mixture under air pressure with variation in binder and additive levels. Corresponding simulations are examined using numerical method of two-fluid modeling or two-phase flow. The result of sand distribution in the slots of the core box base after collision on the wedge is measured and analyzed through the “collision ratio.” The factorial analysis indicates a negative relationship between collision ratio and binder level, while the content of powder additive is highly possible to promote the flow-ability of binder-coated wet sand. The regression analysis also shows that a relationship between collision ratio and COR follows an exponential law. Similarly, the comparison of typical cores from simulation and experiment demonstrates a negative effect on the travel distance of the sand granule when COR decreases. Therefore, the final packing of the sand in the cavity decreases when sand flow-ability is reduced. Practically, for resin-mixed wet sand, it is more difficult to fill the core cavity to achieve full compaction over thin section and sharp corner in the cavity of the core box compared to that of dry resin-coated sand.