Are you still in high school?
If you are interested in jet aeroplanes you should do an Aerospace Engineering course or equivalent at university. Then you should have access to the software you need for designing jet engines/aeroplanes.
Im currently doing my masters year and my university has such software. The programs I have used are Advanced Aircraft Analysis (AAA), Gambit and Fluent for computational fluid dynamics (CFD), there are a few stress analysis programs such as ANSYS workbench and CAD programs are essential for the geometry and layout which can then be imported into the other programs for further analysis.
I hope this is information is useful to you.