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Chapter 12: Problem 34

A certain axial-flow pump has a specific speed of \(N_{x}=5.0\) If the pump is expected to deliver 3000 gpm when operating against a 15 -ft head, at what speed (rpm) should the pump be run? Draw a sketch of the p.ump impeller (front and side views).

Short Answer

Expert verified
To operate against a 15-ft head delivering 3000 gpm, the pump should be run at the speed calculated using the specific speed formula. A sketch of the pump impeller should depict its components and the direction of the flow.

Step by step solution

01

Applying the formula for specific speed

Start by rearranging the specific speed formula to solve for \(N\): \(N=N_{x}H^{3/4}/\sqrt{Q}\)
02

Substituting known values into the equation

The given values are as follows: \(N_{x}=5.0\), \(Q=3000\) gpm and \(H=15\) ft. Substitute them into the rearranged formula: \(N=5.0(15^{3/4})/\sqrt{3000}\)
03

Calculating the Pump Speed

Carry out the arithmetic in the formula to find the speed that the pump should be run at.
04

Drawing a sketch of the pump impeller

This step requires prior knowledge or reference to a figure of an axial-flow pump. Draw a front and side view of the pump impeller. For the front view, draw a circular disc with blades arranged radially around the edge. For the side view, depict the blades as curved lines extending from the center of a circular outline, to show the direction of flow.

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Most popular questions from this chapter

A centrifugal pump having an impeller diameter of \(1 \mathrm{m}\) is to be constructed so that it will supply a head rise of 200 mat a flowrate of \(4.1 \mathrm{m}^{3} / \mathrm{s}\) of water when operating at a speed of \(1200 \mathrm{rpm} .\) To study the characteristizs of this pump, a \(1 / 5\) scale, geometrizally similar model operated at the same speed is to be tested in the laboratory. Determine the required model discharge and head rise. Assume that both model and prototype operate with the same effciency (and therefore the same flow coefficient)

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