Ejector Cones

Ejectors are designed for the full range of operating conditions. The flow cone of the motive gas will change considerably depeding on the entrained gas pressure and this brings geometry into play.

For example, the area of the motive cone can change by more than a factor of two, depending on the Mach No required (see equation below):

The geometry thus has to be arranged to ensure:

Sufficient flow area for the motive cone and the amount of entrained gas required
Diameter of mixing section to meet max/min requirement for supersonic momentum exchange
Correct spacing between supersonic nozzle and mixing section
Get the angles right
Allow space for some recompression upstream of the mixing section, where required.

Ultimately, you need enough energy available (see energy balance) to make it work but you also have to get the geometry right.

Once the design is done and dusted, the actual performance at any operating point can be determined from the energy balance and the geometry.

Don't try this at home! Contact Ezejector for professional assistance :-)