Abstract:A large number of operation practices show that the reliability and stability of large axial flow pump systems will face significant challenges during the start-up process. If the start-up control mode or safety auxiliary facilities of large axial flow pump stations are unreasonable, start-up failure will easily follow. In order to find a scientific control strategy for the start-up of large axial flow pump stations, the start-up characteristics of large axial flow pump stations must be fully understood first.… Show more
“…In the range of 0.3 Q bep ∼1.2 Q bep , both the absolute error of efficiency and the head’s relative error are under 5%, showing that the accuracy of numerical simulation is high. 8,28 In summary, it can be observed that the results of numerical simulation and the model test correlate well, and that the numerical calculation results are true and reliable.Figure 8.Comparison of external characteristics between physical model test and numerical simulation of pump device: (a) Efficiency comparison and (b) head comparison.…”
One of the often employed flow structures in vertical pumping stations is the siphon outlet pipe. It has a complicated geometric structure and internal flow field, which directly affects how effectively, safely, and steadily pumping stations operate. The entire flow conduit of the vertical axial flow pump device was adopted as the study object in order to elucidate the mechanism of the internal biased flow of the siphon outlet pipe caused by the axial flow pump under different flow conditions, and the three-dimensional unsteady flow field of the vertical axial flow pump device was numerically solved using the numerical simulation technique. Physical model tests were used to confirm the results of the numerical simulation. The findings demonstrate that there is a horizontal bias in the flow of the inlet surface and outlet surface of the elbow pipe of the siphon outlet pipe, and that when the flow rate rises, the degree of the horizontal bias in the flow gradually diminishes, and the ratio of biased flow gradually decreases. The flow in hump segment presents up-and-down flow, and when the flow rate increases, the ratios of biased flow first rises before falling. The major causes of the production of biased flow in the outlet pipe are residual velocity circulation at the guide vane's outlet, wall constraint at the elbow pipe, and flow inertia; Under various flow conditions, the morphologies of the vortex structures in the outlet pipe vary; the characteristics of the energy conversion of each part of the pump device are disclosed, with the inlet pipe having the lowest proportion of energy conversion. Under the optimal flow condition, the elbow-inlet pipe's proportion of energy conversion is only around 1.04%, and the proportions of the guide vane, 60° elbow pipe, and siphon outlet pipe's energy conversion are significant and fluctuate with time. The proportion of energy conversion in the elbow-inlet pipe and siphon outlet pipe steadily increases as flow rate rises, but the proportion in the guide vane and 60° elbow pipe drops initially before increasing.
“…In the range of 0.3 Q bep ∼1.2 Q bep , both the absolute error of efficiency and the head’s relative error are under 5%, showing that the accuracy of numerical simulation is high. 8,28 In summary, it can be observed that the results of numerical simulation and the model test correlate well, and that the numerical calculation results are true and reliable.Figure 8.Comparison of external characteristics between physical model test and numerical simulation of pump device: (a) Efficiency comparison and (b) head comparison.…”
One of the often employed flow structures in vertical pumping stations is the siphon outlet pipe. It has a complicated geometric structure and internal flow field, which directly affects how effectively, safely, and steadily pumping stations operate. The entire flow conduit of the vertical axial flow pump device was adopted as the study object in order to elucidate the mechanism of the internal biased flow of the siphon outlet pipe caused by the axial flow pump under different flow conditions, and the three-dimensional unsteady flow field of the vertical axial flow pump device was numerically solved using the numerical simulation technique. Physical model tests were used to confirm the results of the numerical simulation. The findings demonstrate that there is a horizontal bias in the flow of the inlet surface and outlet surface of the elbow pipe of the siphon outlet pipe, and that when the flow rate rises, the degree of the horizontal bias in the flow gradually diminishes, and the ratio of biased flow gradually decreases. The flow in hump segment presents up-and-down flow, and when the flow rate increases, the ratios of biased flow first rises before falling. The major causes of the production of biased flow in the outlet pipe are residual velocity circulation at the guide vane's outlet, wall constraint at the elbow pipe, and flow inertia; Under various flow conditions, the morphologies of the vortex structures in the outlet pipe vary; the characteristics of the energy conversion of each part of the pump device are disclosed, with the inlet pipe having the lowest proportion of energy conversion. Under the optimal flow condition, the elbow-inlet pipe's proportion of energy conversion is only around 1.04%, and the proportions of the guide vane, 60° elbow pipe, and siphon outlet pipe's energy conversion are significant and fluctuate with time. The proportion of energy conversion in the elbow-inlet pipe and siphon outlet pipe steadily increases as flow rate rises, but the proportion in the guide vane and 60° elbow pipe drops initially before increasing.
“…The authors of [17] investigated the effect of blade number on the internal flow condition of a high-specific-speed centrifugal pump. The start-up characteristics of large axial flow pump systems and the challenges they face during the start-up process are investigated in [18].…”
This editorial discusses the importance of Advanced Fluid Machinery in the sustainable development of energy. Fluid machinery is crucial in many engineering applications, including aerospace, civil, mechanical, and chemical engineering. This Special Issue, entitled “Optimization and Flow Characteristics in Advanced Fluid Machinery”, features several research articles exploring flow characteristics and optimization in fluid mechanics. The authors present innovative ideas, methodologies, and techniques to advance the field of fluid mechanics. The papers cover a wide range of topics, including computational fluid dynamics (CFD), turbulence modeling, heat transfer, multiphase flow, and fluid–structure interactions. The articles featured in this Special Issue also investigate the relevant hydrodynamic attributes of turbomachinery, high-pressure jets, marine propulsion systems, and internal combustion engines to a considerable extent, significantly expanding the scope of research within the Special Issue.
In order to study the influence of regulating valve openings on the dynamic characteristics of the rotor structure of a multistage pump during the transient startup process, a seven-stage pump was selected as the research object. The transient startup of the pump was jointly simulated using Flowmaster and CFX, and the deformation law of the rotor under different valve openings with time was investigated through Workbench. The results showed that the deformation trends of the impellers at each stage were similar under different valve openings during transient startup, and regulating the valve opening had little significant impact on the stability of the rotor structure. The maximum deformation of the pump shaft occurred at the contact surface between the intermediate impeller and the pump shaft under different valve openings. As the valve opening increased, the maximum deformation of the pump shaft decreased slightly. This study reveals the structural characteristics of the multistage pump during the transient startup process under different valve openings, which is of great importance for improving the safety and reliability of multistage pumps during emergency operations.
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