Geometry Vari­a­tion of a Fuel Injector Design

When it comes to the opti­miza­tion of e.g. diesel engines, we have another inter­est­ing com­po­nent for you: the fuel injector! Basi­cally, this com­po­nent takes care that the fuel is opti­mally sprayed into the com­bus­tion chamber. This pretty sophis­ti­cated product is an impres­sive engi­neer­ing and man­u­fac­tur­ing master piece (BTW: Every­thing is really tiny!). We recently needed to come up with a quick method to change the existing nozzle geometry of a fuel injector. The geometry was imported into CAESES®, using the STL format. The fol­low­ing screen­shot shows a slightly changed design of what we had worked on: 

CAESES® offers the pos­si­bil­ity to apply so-called free form defor­ma­tions to existing geome­tries. So this is what we did: We created a box around one of the nozzles, and defined some expan­sion strate­gies. With this, the nozzle could be enlarged and even fully changed in its shape. Sure, there are lim­i­ta­tions in terms of man­u­fac­tur­ing etc. But at this point in time, we tried to set it up as flexible as possible. Here is a screen­shot of the setup where the outer geometry was removed for visu­al­iza­tion purposes:

In a next step, we defined design vari­ables for the expan­sion factors, to make it ready for auto­mated studies. The fol­low­ing ani­ma­tion shows the defor­ma­tion box and the effect on the geometry: 

When we finished this setup for the nozzle, we applied it to the other nozzles, i.e. they were changed in the same way. We handed over the entire setup to the engineer who requested this shape changes. Being the expert in this field, he simply con­tin­ued to fine-tune things a little bit further, accord­ing to his tech­ni­cal require­ments and con­straints. Finally, he run design studies where the entire process was fully auto­mated (geometry changes / meshing / CFD analysis). For illus­tra­tion purposes, here is a set of ani­ma­tions that show some auto­mated shape changes: 

More Infor­ma­tion

Free form defor­ma­tions are part of our pro edition of CAESES®, and it nicely com­ple­ments the general CAD func­tion­al­ity for CFD engi­neers. In similar projects, we created a fully-para­met­ric model for injec­tors (instead of deform­ing an existing one), which usually gives you even more control, while at the same time the number of vari­ables can be reduced.