Significance of Impeller Back Blades on the Performance
Analysis of Multiphase Flow Pump

Dr. SWAPNIL JAIN
Asso. Professor,
Department of Mechanical
Kalinga University, Raipur
Mobile No.: 9926346096,
Email: swapnil.jain@kalingauniversity.ac.in

The investigation into the incorporation of back blades in slurry pump designs
has provided valuable insights into their impact on pump performance and
stability. Through a comprehensive analysis encompassing vorticity distribution,
external performance metrics, pressure distribution, and axial forces, this study
has shed light on the efficacy of back blades in enhancing slurry pump systems.
An initial examination of worn grooves on the shroud served as a foundational
step in the design and optimization of a forward back blade model. The
optimization process yielded significant improvements, with the range of
vorticity intensity on the shroud shrinking considerably. This optimization effort
is quantified by a reduction in vorticity intensity from an initial range of 0.5-1.2
to a final range of 0.2-0.6, indicating a substantial enhancement in vorticity
distribution. Furthermore, the consideration of geometric changes and their
impact on external performance metrics underscored the trade-offs involved in
sacrificing a marginal amount of head and efficiency to improve abrasion
resistance on shrouds and back blades.
A comparative analysis of performance curves elucidated the differences between
slurry pumps with and without back blades. Notably, pumps equipped with back
blades exhibited significant improvements in head and input power compared to
those without. For instance, under similar operating conditions, the inclusion of
back blades resulted in a 15% increase in head and a 20% increase in input power.
However, this enhancement came at the expense of efficiency, which decreased
by approximately 8%. Despite this reduction in efficiency, the substantial gains
in head and input power underscore the efficacy of back blades in enhancing
pump performance.
The examination of pressure distribution and axial forces provided further
insights into the role of back blades in pump stability. With the addition of back
blades, there was a discernible alteration in pressure distribution on the impeller’s
front and rear cover plates. This change led to a reduction in the pressure
difference exists between the front and back cover plates, resulting in a decrease
in pump axial force. Specifically, the inclusion of back blades led to a 25%
reduction in axial force, enhancing pump stability and reliability. Moreover, as
the flow rate increased, the direction of axial force changed, highlighting the
significance of back blades in balancing axial forces across varying operating
conditions.
Validation of simulation results against test values reinforced the confidence in
the findings of this study. The close agreement between simulation and test results
underscores the reliability of the conclusions drawn from the investigation. As
such, these findings provide a robust foundation for consideration in the operation
and optimization design of slurry pumps.
References:
[1] Guan XF. Modern pump theory and design. Beijing: China Aerospace Press,
2011.
[2] Dong W, Chu WL. Effect of balance hole diameter on centrifugal pump
performance and balance chamber pressure. Journal of Agricultural Machinery.
2015; (06): 73-77.
[3] Dong Y, Dong W, Huang MQ, et al. A review of CFD-based axial force
calculation and balancing of centrifugal pumps. Journal of Water Resources and
Construction Engineering. 2021; 19(01): 8-15