Study on energy loss of stepless stratified water intake at power generation inlets based on entropy production

Abstract

[Objective] Local flow disturbances caused by changes in gate leaf combinations and water intake layers in stepless stratified water intake systems are difficult to quantitatively characterize using traditional head loss methods. To address this challenge, their dissipation characteristics and spatial distribution patterns under complex structural conditions are investigated, thereby providing methodological support for the identification and optimization of energy losses under complex hydraulic structures. [Methods] Based on the entropy production theory, an analytical framework for sub-item energy consumption was constructed. On the basis of verification through a 1∶20 physical model test, three-dimensional numerical simulation was used to quantitatively analyze the viscous dissipation(EPDD), turbulent dissipation(EPTD), and wall friction dissipation(EPWS) of the inlet system under typical operating conditions. [Results] The results showed that the total entropy production of the system increased with the upward movement of the water intake layer. High-level water intake triggered drop impact and shaft flow reconstruction. The shaft section was the main dissipation zone, and the maximum entropy production of the system reached 2 800.468 W·K^-1. The entropy production contribution of the stepless stratified water intake device remained below 8% under different operating conditions, indicating good hydraulic stability. EPTD was the dominant dissipation mechanism, accounting for more than 98% of the entropy production in all operating conditions. Local high-dissipation regions were mainly concentrated in the gate leaf-cross brace junction, shaft drop zone, and pipeline inlet region. [Conclusion] Entropy production theory can effectively reveal the spatial distribution and underlying causes of energy loss in complex hydraulic structures, offering greater diagnostic depth and optimization guidance than traditional head loss methods. The findings clarify the relationship between structural disturbances and energy consumption distribution in stepless stratified water intake systems, providing theoretical support for system structural optimization and operational scheduling and holding significant implications for improving system energy efficiency and operational safety.

Keywords

stepless stratified water intake / entropy production / energy loss / numerical simulation / structural optimization