(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Hi guys, Ive been working on some problems at uni to try and get to know this subject better and i have been unable to answer a question.

the impellar of a centrifugel pump has the following configaration,

diameter 254 (hence r2=127) blade exit angle (Beta) 32degrees, effective outlet area=0.017m^2, Speed (N)=1450 rpm (hence omega =151.84 rad/s). the diameter of the suction and delivery openings are 150mm and 125mm. delivery rate is 30.8l/s, pressure heads at suction and delivery are 4.5m and 13.5 m below and above respectively(atmospheric), pump motor is 8.28Kw. Alpha 1 is 90 degrees due to shockless entry and the actual tangential velocity at impeller outlet is 0.7 of the ideal. Determine

1. the overall efficency

2. the hydraulic efficency based on the actual tangentail velocity at blade outlet.

2. Relevant equations

I have used for the hydraulic efficency

actual head developed by pump/theoretical head developed by impleller.

vbar^2/2g energy loss in impeller

(u2*vbart2)/g ideal head

ideal head-energy loss = actual

3. The attempt at a solution

i have for my values

u2=19.28

vbarn2=2.27

vbart2=15.64 15.64x0.7=10.95

vbar2=15.77

when i calculate for the hydraulic efficency i get 71% when the answer is 80% and i cant seem to get far enough in the first part to get an answer for it, but the correct answer for part one is 66%.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Fluid systems centrifugal pumps

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**