So you're just looking to animate the assembly components to see the impeller or whatever moving, perhaps with a section view or something?
Or are you interested in seeing simulation data while it is moving?
If you have simulation, then you have access several motion/animation tools in SolidWorks.
If you make a post under the motion section on the forum outlining your specific needs, you will probably get more responses than in this section. There's a variety of gurus for all types of applications who can help you out.