WAVE FORMATION IN AN ENCLOSED CONDUIT IN DIE CASTING

Transition from a free surface flow to pressurized flow through hydraulic jump appears in several situations, which include the die casting cold chamber process, flow in sewer systems after a large rain storm, turbine tailraces, and in power plants during pipe failure. The study presented here is general, but with special interest in the application to a 10 billion die casting industry. One of the main problems in die casting is the product integrity due to porosity. Experiments have shown that there is a critical plunger velocity for which less air is entrained and thus the porosity is reduced. Earlier researchers approached this problem assuming that the energy is conserved. A comparison between the “energy conservation” model and the available experimental data presented here demonstrates that the energy is dissi-pated. Consequently, “the energy conservation” model under estimates the plunger velocity required for avoiding air entrainment. A model based on momentum conservation has been established, which is shown to be in a reasonable agreement with the limited available experimental data. Critical plunger velocity, Die casting operating parameters, Turbulence, Jump conditions, Shot Sleeve.