Chemical Engineering - Fluid Mechanics - Discussion

Why Other Options Are Incorrect?

Monotonically decreases: Incorrect because the pump is highly inefficient at zero flow (shut-off head) due to high turbulence and recirculation.
Efficiency must go up before it can go down.
Decreases and then increases: Incorrect because this describes a U-shaped curve, which is the exact inverse of a standard pump performance characteristic.
Remains constant: Incorrect because a centrifugal pump's hydraulic efficiency is highly dynamic and intrinsically tied to the velocity vectors and fluid flow rates entering the impeller.

The correct answer is D.

I think option D is the correct answer.

I think option D is the correct answer.

According to me, option D is correct because when we plot a curve between flow rate and efficiency shows same.

From Pump Characteristic Curve, With an increasing flow rate, the hydraulic efficiency of a centrifugal pump first increase to the peak efficient point and then decreases.

The correct answer is option D.

I think D is the correct answer.

Monotonic means there is no constant value. When the efficiency starts falling it falls sharply or continuosly in this case.

Hydraulic efficiency of the pump is defined as the ratio of fluid Power to absorbed power. This efficiency is maximum only at one capacity value. It is lower in other capacities.

So the correct answer should be; increases and then decreases.

Thanks all for explaining the answer.