الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
To imporve the hydraulic perfrmance of centrifugal pumps , first it is needed to predict its performance.
In the present work a mathematical model is constructed to predict the centrifugal pump performance at a rang from 0% to 110% of the designed discharge. This model is based on full analysis for pump losses at designed flow rate and using Euler’ s equation mines hydraulic losses at designed of manometric heah at best efficiency point. The prediction at off design condition is based on a statistical method, which relates pump performance to its performance at best efficiency point. The model represents the effect of number of blades on impeller friction loss and circulatory loss, and makes an optimization for the number of blades for the model pump.
Moreover the results of the prediction model for the standard impeller at different running speeds, show that the similarity rule is satisfied.
Tese prediction result leads to the idea of using non-complete blades between each two complete blades, in the present work it is called shorted blades.
A test rig for testing centrifugal pump with different impellers at different shorted blade lengths is constructed.
Five impeller configurations with different shorted blade legths of 39%, 24%, 17%,12%,and 6% of the full blade length are manufactured. These shorted blades impeller configurations have inlet diameter for the shorted blades of 0.7, 0.8, 0.85, 0.9 effect of these shorted blades on pump performance .
The experimental results ahowed that, there are improvements in head and efficiency by 9% and 8% from the standard impeller for the impeller of shorted blades of inlet diameter of 0.8 of the exit impeller diameter .
The improvements are due to imbedding of shorted blades between each two complete blades reduce the circulatory loss and improve the flow velocity profile at impeller exit which reduce also the mixing losses at volute entry. Some of the others shorted blades lengths have a little effect on the performance because their length is so long that the increase in friction loss dominates the reduction in circulatory loss.
Further more, the very short-shorted blade is not long enough to reduce the circulatory loss, while it increase the distortion of flow velocity at impeller exit.
In addition, for the optimum shorted blade length a flattening in head-capacity curve is observed.
Comparison between mathematical model and experimental results for the standard impeller at different rotational speeds are generally in a good agreement.