Internal flow investigation of a centrifugal pump at the design point

Abstract

The unsteadiness of the flow at the leading edge of a vaned diffuser represents a source of low efficiency and instability in a centrifugal pump. Furthermore, the internal flow of the impeller can be affected by asymmetric downstream conditions, which results in extra flow unsteadiness and instabilities. The improvement of machine performances can only be achieved if there is a progress in the comprehension of the nature of the complex flow that develops at the gap between the rotor and the stator.This paper presents the results of LDA investigation of the internal flow of a centrifugal pump equipped with a backswept impeller and a vaned diffuser. The data taken in phase with the impeller rotation are presented as animated frames reconstituting a temporal evolution of the flow in radial planes at the diffuser inlet.

Numerical Analysis of Centrifugal Impeller for Different Viscous Liquids

“…5. The velocity vectors at inlet and in impeller passage represent smooth flow and no separation of fluid is observed as reported by the researchers [5,8,25]. …”

“…They concluded that the velocity and pressure distribution of seven-bladed impeller coincides with the numerical solution whereas three-bladed impeller deviated largely from numerical solutions both at the design and off-design conditions. Liu et al [7], Akhras et al [8] have reported that impeller flow separation was observed on blade surface at off-design flow rate as compared to smooth flow. As reported by researchers [3][4][5], flow field within impeller passage is highly complex and depends on flow rate, number of blades, blade curvature and specific speed.…”

Comparison of Periodic Flow Fields in a Radial Pump among CFD, PIV, and LDV Results

“…Compared with PIV, Laser Doppler Velocimetry (LDV) is more time-consuming but gives more accurate results due to the measurement directly on the points of interest. LDV measurements conducted in radial pumps have been reported by Akhras et al [15], Hajem et al [16], Pintrand et al [17], and Akhras et al [18].…”

Investigation of unsteady flow in a centrifugal pump at low flow rate

“…In order to obtain inner flow characteristics, many researchers applied experiment and simulation to investigate the unstable flow. Pedersen et al, 2 Liu et al, 3 and Akhras et al 4 applied the laser Doppler velocimetry (LDV) technique to measure the velocity field of the impeller passages and reported that flow separation occurred in blade surfaces under off-design conditions. Hong and Kang 5 and Hagelstein et al 6 studied the unsteadiness of the flow field at the impeller exit and volute separately to research the pressure distribution in the case of impeller-volute interaction.…”