| description abstract | Centrifugal pumps are used in a variety of engineering applications, such as power production, heating, cooling, and water distribution systems. Although centrifugal pumps are considered to be highly reliable hydraulic machines, they are susceptible to a wide range of damage due to several degradation mechanisms, which make them operate away from their best efficiency range. Therefore, evaluating the energy efficiency and performance degradation of pumps is an important consideration to the operation of these systems. In this study, the hydraulic performance along with the vibration response of an industrial scale centrifugal pump (7.5 KW) subjected to different levels of impeller unbalance was experimentally investigated. Extensive testing of the manometric pressure head, flow rate, shaft power and efficiency along with vibration measurements were carried out to evaluate the effects of various levels of impeller unbalance on the pump hydraulic performance. Both time and frequency domain techniques coupled with principal component analysis (PCA) were used in this evaluation. The effect of unbalance on the pump performance was found to be mainly on the shaft power, while no change in the flow rate and the pump head was observed. As the level of unbalance increased, the power required to operate the pump at the designated speed increased by as much as 12%. Also, the PCA found to be a useful tool in comparing the pump vibrations in the field compared to the baseline vibration of the new pump in order to determine the degree of the impeller unbalance. The results of this work can be used to evaluate and monitor the degradation in the pump performance to set the allowable operating conditions and enhance the preventative maintenance programs. | |
