Question

Why centrifugal pump casing is called involutes casing?

Answer 1

Answer:

$\huge\underline\mathfrak\orange{ANSWER}$

Yes it does look like an involute that's why it is called involute casing. The main reason behind this is that as the fluid moves through the casing some amount passes through the runner so, Q decreases and thus the velocity tends to decrease.

Answer 2

Answer:

As the fluid moves through the casing some fluid is some amount pass through runner.