It’s happened to many of us, that we’ve looked inside some appliance and found there to be a very small air-blower, powered by a very weak motor. And so one response which some of us might have, would be to think ‘That’s not a true turbine, because it’s not a meter in diameter, and wasn’t designed by steam specialists.’
But you see the fact remains, that according to Engineering, this turbine is either a blower or a compressor. In this case I’ll guess it’s a blower.
The fact that it’s a small object, spinning uselessly at high RPMs, working on small quantities of air, wouldn’t change this.
And the part of that which people may overlook, is that the efficiency of such a ‘small wheel’ will still depend on how well its blades have been computed and curved. The fact that this wheel is working with small amounts of energy, is orthogonal to the question of what its efficiency is. Hence, if the small wheel actually resembles blocks of plastic which have been stamped out or 3D-printed cheaply, the efficiency will suffer. OTOH, If the design was sophisticated, it’s possible for such a small wheel to produce surprisingly strong suction or pressure, and to convert a small amount of Electricity into that.
Mind you, it’s not in my habit to be taking every device apart, to see how well its small turbines were in fact computed. I’ve seen a few, that looked primitive, and from which I’d expect poor results.
Now, if it takes a remarkably long time for this turbine to get up to speed, and yet to do so reliably, what this means is that the “Moment Of Inertia” of what’s spinning is high, compared with the available Torque from its motor. Just like there is linear inertia, there is also this angular inertia, which differs by default, according to which axis we choose to try to spin an object along – unless the object has a spherical distribution of mass.
Would the observer think that the spinny thing is hard to spin, due to high moment of inertia? If not, this would seem to mean that its motor is only capable of generating Weak Torque. If at that, high RPMs and good performance are reached from the turbine, I’d say that this could be a sign of the system being efficient, once in its equilibrium state (of a controlled RPM).