Abstract
Pump as turbines (PATs) are widely applied for recovering the dissipated energy of high-pressure fluids in several hydraulic energy resources. When a centrifugal pump operates as turbine, the large axial vortex occurs usually within the impeller flow passages. In view of the structure and evolution of the vortex, and its effect on pressure fluctuation and energy conversion of the machine, a PAT with specific-speed 9.1 was analyzed based on detached eddy simulation (DES), and the results showed that vortices generated at the impeller inlet region, and the size and position of detected vortices, were fixed as the impeller rotated. However, the swirling strength of vortex cores changed periodically with double rotational frequency. The influence of vortices on pressure fluctuation of PAT was relatively obvious, deteriorating the operating stability of the machine evidently. In addition, the power loss near impeller inlet region was obviously heavy as the impact of large axial vortices, which was much more serious in low flow rate conditions. The results are helpful to realize the flow field of PAT and are instructive for blade optimization design.
Highlights
In recent decades, pump as turbine (PAT) has drawn increasing attention in energy recovery systems where a high-pressure water source exists
The grid convergence and grid tests were performed, and the results showed that the head–flow rate curve became stablebecame as the independence tests were performed, and the results showed that the head–flow rate curve elements of mesh over of
The boundary condition of the inlet was the total pressure with an initial value of 0.5 MPa, and the outlet was the flow rate with an initial value of 50 m3/h for design condition; the rotational speed of the impeller was fixed with 1500 r/min
Summary
Pump as turbine (PAT) has drawn increasing attention in energy recovery systems where a high-pressure water source exists. A detailed analysis of the turbulence flow structure better understand energy recovery behavior and to theSingh best efficiency operation of a pump and its the reverse mode were system performed by Pascoa et reach al. The reverse flow causes great deal of the vortex inbehavior impellers.ofStanbli et al. The structure and evolution of the large axial vortex in impeller channels were revealed, and its PAT during start-up process using numerical-based method. The results can be fluctuation expected toinbestator a support stator interactions in turbine mode losses of a pump and presented the pressure flow for the optimization design of PAT. The large axial vortices and pressure fluctuation In thisoperation, research, this the phenomenon flow behavior of PAT wasserious simulated by theofCFD induced reasonably.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
