Gas-Solid Two-Phase Flow Simulation of Coaxial Powder Delivery Nozzle in Rapid Prototyping

Abstract

Coaxial powder delivery nozzle plays an important role in metal part direct and rapid prototyping technology and the reasonable structure can ensure uniform and stable flow of metal powder. Gas-solid two-phase flow theory is considered to simulate outside flow field of carrying gas-type coaxial powder delivery nozzle. The physical and mathematical models are erected. FLUENT software is used to simulate the velocity distribution of gas and solid particle, the volume fraction distribution of particle and the focusing properties. The simulative results indicate that both the structure of coaxial powder delivery nozzle and inlet velocity affect the convergence of powder. When the metal powder is only driven by the carrying gas without the shield gas flow, the powder appears focusing and the focus is 8mm far from the nozzle exit, but the volume fraction at the focus is only 2.6 percent, which shows the convergence of powder is not good and the usage rate is not high. In the optimized structure the simulative results show that the powder flow is affected by the flow of shield gas. When the velocity of shield gas is 6m/s, the powder shows good convergence and the volume fraction of powder at the focus reaches 3.3 percent. The higher the velocity of shield gas is, the more uniformly the powder flows, but the volume fraction at the focus is slightly lower. It is obvious that the numerical simulation will benefit for coaxial nozzle designing and performance improving.

Research on Structural Parameters of Conical Nozzle

“…Some scholars had studied the inner flow field of nozzle with numerical simulation. Most of these studies had not involved structural parameters design of conical nozzle [3][4][5][6]. Water jet assist cutter cutting deep-sea mineral is a new mining method.…”

Influence of different central nozzle diameters and powder injection rates on carbon powder mixed injection with shrouding supersonic oxygen jet (CMISSO) lance

“…Although a large number of studies have tried to increase the powder velocity and improve its utilization efficiency [8,10,15,16], as a new method, how the dynamic characteristics of CMISSO lance are affected by the central nozzle diameter and powder injection rate has not been reported.…”

“…The results show that the lime powder tends to aggregate with the increase of powder injection rate. Wang [16] used FLUENT software to simulate the velocity distribution, volume fraction distribution and aggregation characteristics of gas – powder mixed injection in the coaxial powder delivery nozzle to optimize the nozzle design.…”