Session: Student Poster Competition

Submission Number: 187038

Dynamic Mechanism of Energy Loss in Centrifugal Pumps Under Off-Design Conditions 

Due to variations in pipeline system pressure and flow rate, centrifugal pumps frequently operate at off-design conditions which significantly impacts their performance. Operation under off-design conditions induces disordered internal flow patterns and leads to a sharp decline in efficiency. This study proposes a dynamic decomposition method for energy loss based on numerical simulations of a full-pipeline system. The validity of the proposed model has been confirmed through experimental verification.

While Dynamic Mode Decomposition (DMD) is currently primarily applied to pressure and velocity fields, this study innovatively applies it to the decomposition of energy loss. The feasibility of this approach is demonstrated through the reconstruction analysis of energy loss. Based on this method, the evolution mechanisms of flow structures and energy losses within the pump under various operating conditions are revealed.

The results indicate that the entropy production rate (EPR) can be decomposed into a time-averaged component and fluctuating components at distinct frequencies. Under low flow rate conditions, both the time-averaged and fluctuating EPRs are high, with the spatial distribution of entropy production exhibiting significant non-uniformity. Under high flow rate conditions, the time-averaged EPR is substantial due to friction and shock losses. The fluctuating EPR and its spatial non-uniformity under design conditions are relatively similar to those observed under high flow rate conditions. Furthermore, through the reconstruction of low-frequency EPR, the locations of low-frequency entropy production across the three operating conditions are identified. Low-frequency entropy production is predominant under low flow rate conditions, primarily induced by recirculation near the impeller blade inlet and outlet.

This study elucidates the mechanisms of internal energy loss within the centrifugal pump impeller under different operating conditions, providing theoretical support for extending the high-efficiency operating range of centrifugal pumps. Additionally, the proposed method holds promising potential for application in the analysis of other turbomachinery.

Presenting Author: Xinxiang He Zhejiang University

Presenting Author Biography: Xinxiang He is a Ph.D. candidate at Zhejiang University, specializing in high-efficiency and low-fluctuations design of turbomachinery. He has published a first-author paper in the journal Energy on energy loss analysis of centrifugal pumps under different working conditions, and has co-authored papers in Journal of Fluids Engineering and Applied Thermal Engineering on flow flied analysis and optimization design of turbomachinery.

Authors:

Xinxiang He Zhejiang University
Peng Wu Zhejiang University
Dazhuan Wu Zhejiang University