Exam Question

(a) Centrifugal pumps rely on centrifugal force to displace fluid from the center to the periphery. For effective operation, they need a continuous flow of liquid at the input center (eye of the impeller). In a centrifugal pump, the centrifugal force generated is insufficient to move air or vapor because the mass of air (density ~1.2 kg/m³) is much lower than that of water (density ~1000 kg/m³). The equation governing centrifugal pump lift in terms of water mass is:
Mw * r * ω^2 > ρw * g * h
where Mw is the mass of water, r is the impeller radius, ω is angular velocity, and ρw is water density. For air, due to its lower density, the centrifugal force Ma * r * ω^2 is too low to overcome the gravitational force needed for lift, resulting in no suction lift.
On the other hand, turbo-blowers, also centrifugal machines, can handle air because the required centrifugal force is feasible for the lower density of air. In turbo-blowers, the centrifugal force: