I've been working on this off and on for a couple of weeks and think it's ready for a public test release. It's an addon for Blender with scripts that allow creating, exporting and importing Vector fields for UE4 using the fga file format. It's my first attempt at an exporter/importer from scratch, but seems to work surprisingly well :D
The editor allows the velocities of particles in a volume to be saved after influencing the system with the different force fields available in Blender. Any type of particle simulation Blender can do can be used for this (smoke, fluid, any force field).
I'll be writing the documentation this week, but a basic how-to is available in the Readme on Github. Performance is surprisingly good considering this is written in Python and the amount of particles that the scripts can interact with. I plan to post a link on the UE4 forum after some more testing and polishing.
Download here (Github)
Example .blend File