Hello dubai3d.

The type of explosion in your sample image shows an explosion that has a type of heat dynamics called "PyroClastics".

This can ONLY be achieved correctly in Maya with a Fluid simulation. i.e voxels with volumetric self shadowing properties.

The samples in the visor such as the "Blast, Fireball, Nuke & Nuke2d are examples you should try to render.

NOTE: You must renser the WHOLE sequence, not just one frame.
Once the WHOLE sample sequence is fully rendered, you will see the pyroclastic effects as fuel is born into the voxel volume.

The best way I have found to learn Fluids are with a more comprehensive training program such as those found in a Maya Master Class, or a dvd training video.

There are many out there to choose from, simply do a google search and you should have no issue finding them.

Good luck!