In the current work, flow visualization and numerical simulation by ANSYS-FLUENT of a centrifugal pump with a semi-open impeller are utilized to verify that decreasing the speed will decrease the formation of air bubbles and hence cavitation occurrence possibilities. The purpose of the current work is to utilize two different test rigs; pumping systems, to verify that each pumping system nearly has the same reduction percentages in cavitation occurrence for the same reduction percentages of speed. This study compares two centrifugal pumps with different capacities, whereas the first pump is 0.5 hp and the second is 2 hp. They pump water using two different pumping systems with two different percentages of speed reduction for the two pumps. The results indicated that the suction pressure, which represented an indication of the cavitation status was increased due to the percentages of speed reductions of 6% and 12% (related to full pump speed) for the first pump by 8% and 21% and for the second pump by 8% and 19%, respectively.
Computational Fluid Dynamics (CFD) numerical simulation and experimental investigations are performed on three different speeds of two laboratory centrifugal pumps with a Plexiglas casing. Numerical simulation findings show that there is an acceptable agreement with the experimental work, with an error percentage of 8.5% for the best case, and it was insured that the speed reduction by the above percentages is an active procedure to reduce the harmful effect of cavitation.