Computer-aided design of a centrifugal pump stage: A head prediction methodology at zero flow rate

The article presents a methodology for predicting head at zero flow rate for various types of centrifugal pump stages. This methodology is intended for integration into existing software designed for the design of flow paths of centrifugal pump stages. During the research an experimental dataset on the flow passages of boiler feed and end-suction centrifugal pumps is collected and systematized. The authors perform the statistical processing of the results and regression analysis, which reveals the degree of influence of the specific speed coefficient on the head coefficient at shut-off. The research derives a formula for the head coefficient at the zero-flow point as a function of the specific speed coefficient, the number of impeller blades and the blade outlet angle for the following configurations: end-suction centrifugal pumps with and without axial thrust balancing; intermediate stages of boiler feed pumps; boiler feed pump stages with axial inlet, with and without a stator. Additionally, the authors propose a criterion for preventing the drop (sagging) of the headcapacity curve. Based on the obtained dependencies, the module for predicting the stage performance characteristic is modernized for the computer-aided design system for centrifugal pump stages “CAD of Centrifugal Pumps”. The research also validates the calculated values of the head coefficient at zero flow rate against experimental data; the resulting deviation does not exceed 6 %.