I decided to test a program called motion 2 for particle effects for game particles.
128 x 128 in size,TGA format -32 bit, alphas should be in there as well from export options, black backgrounds
each cell is isolated to its own file, I didn't stitch them into a 2d plate but its easy enough to load them.
3 different explosions as substitutes until you find what your looking for.
download from this post is free for non - commercial use.
if you really want to use them for commercial purposes i guess thats ok as well.
for some reason both upload options wont let me upload 4.2 megs weird.
ill try and upload them separately