Investigations of energy distribution and loss characterization in a centrifugal impeller through PIV experiment.

The objective of this study is to explore a method that can describe the loss distribution trend of flow field directly through the PIV experiment. Three main concepts, namely Local pressure head increase (H pr), Local velocity head increase (H vr) and Local pump degree of reaction (λ), are proposed to characterise the energy distribution in the impeller. Results show the distribution of H pr is affected mainly by the inlet flow field of the impeller passage, while the maximum value region of H vr along the radial direction is located at the downstream of the unstable region on the blade suction side and in the center of the unstable region in the pressure side. These distributions are due to the local increase of absolute velocity (C) caused by vortex motion. The large vortex is dispersed along the suction side of the impeller blade, causing the energy losses to become more obvious than in the pressure side. The developing trends of the pump efficiency and passage-averaged λ as the flow rate increased are consistent. Consequently, the distribution of loss intensity in the flow field can be quantitatively reflected by λ. • Three concepts are proposed to characterise the energy distribution in the impeller. • The distribution of H pr is determined by the flow pattern at impeller entrance. • The distribution of H vr is affected by the vortexes in the impeller passage. • Losses caused by vortices along the blade suction side is more obvious than that on the pressure side. • The distribution of loss intensity is quantitatively reflected by the λ. [ABSTRACT FROM AUTHOR]