Download Free 3D Model Vacuum Ejector 3D Print Model

Summary
This is a vacuum ejector designed for compressed air to vacuum generation. Advantages of this type of vacuum generation is that it is instant when compressed air is applied it starts generating vacuum. Also, it can handle contaminants in the vacuum flow. As long as the contaminants being ingested in the vacuum port are smaller that the mixing tube diameter (3mm in this case) the ejector will not be blocked.
The input port injects compressed air that is exhausted on the output port. Air in the mixing chamber is entrained in the flow and a vacuum is developed. I have measured 18.5″ of mercury (-9PSI) on the vacuum port with 0 flow. I don’t have a flow gauge so I can’t judge efficiency or flow with an open input.
Graphs with the input pressure and vacuum achieved are attached.
Both the compressed air input and vacuum ports are designed to be tapped with a 1/4″ NPT thread. The wall taper matches the NPT thread and allows easy connection to air fittings.
Print Settings
Printer Brand:
Wanhao Printer:
Duplicator 6 Rafts:
No Supports:
No Resolution:
.1mm layer height Infill:
25% Notes:
Using Simplify3d variable thin wall extrusion can help print quality with the fine features. A minimum of 1.6mm wall thickness is needed to avoid the NPT tap from breaking through.
How I Designed This
This design was based of research on steam ejectors and air vacuum generators. There is little useful documentation on the design of these I have found. There were three previous version that did not perform as well (max 5″ of Hg) before I looked at steam ejectors.
The main improvement is the ratio between the expansion tube and the length of the expansion tube. The initial designs had short expansion tubes, but a ratio of 7 for the expansion tube diameter to length greatly improved things.
Since this design tops out at ~75psi, I suspect that I need to look at the mixing tube diameter to prevent supersonic flow. This should improve performance at higher input pressures.