Approximate method for calculating the characteristics of a radial flow pump

Abstract

Similarity in flow patterns between fans and pumps provides the possibility of suggesting an approximate method for calculating radial flow pump characteristics. The proposed method uses relations expressing the energy balance of real fluids. Calculations of velocity triangles are given for a flow ahead of an impeller operating in sections with half-output, recognized as an average value. The results followed the expression within blade theory for radial impellers. While the exit angle helps to understand the blade shape at the no-lift position, the impeller losses, on the other hand, are related in a certain way to the angle of incidence. Losses at different elements of the pump are treated, at a selected point of operation, as having a constant coefficient of loss. Values of losses are calculated from the actual pressure heads. The flow through spiral bodies takes an approximate kinetic model. A spiral section having the shape of a circle provides the suitable conditions guaranteeing the operation of a single impeller along its circumference while still having the same optimum value of pump efficiency. The illustrated figures are the result of calculations made on radial impellers measured from several pump investigations.