Evaluation of the Accuracy of Centrifugal Pumps Complete Characteristics and Their Approximation Using Fourier Series

The complete characteristics used by commercial codes to simulate failures in pumping systems encountered e.g. in power plants, date back many decades. Since then, pump design methods have changed, resulting in, among others, the increase of their efficiency and the stability of characteristics. There is a need to see how these changes have affected the complete characteristics in a full range of pump operation. In the article, it is shown that the new complete characteristics give different failure simulation results than the old ones. Describing the dynamic pump operation, understood as determining the basic parameters that change at any time, such as: flow, lifting height, driving torque and rotational speed, is very important, especially for large installations whose operation is of key importance. A convenient form for analysing dynamic states are Suter functions based on inverse trigonometric functions, because they allow showing all pump operating states using one continuous (other than e.g. spline) function. Therefore, as an approximation of the exact characteristics, Fourier harmonic functions were proposed. The effect of the approximation on the accuracy of the simulation was checked.