Abstract
Rotating stall, which is a common phenomenon in turbomachinery, strongly relates to the flow rate condition. In centrifugal impellers, rotating stall was induced by the incidence angle on blade leading-edge at partial-load. The blade leading-edge shape also influences the rotating stall because of the subtle change of local flow-field. In this study, the influence of blade leading-edge shape on rotating-stalled flow characteristics was studied in a six-blade centrifugal pump impeller. The stall pattern was “alternating”: Three passages were stalled, three passages were well-behaved, and the stalled and well-behaved passages occurred alternately. The stalled flow characteristics can be studied without the interruption of stall cell movement. Four types of blade leading-edge (blunt, sharp, ellipse, and round) were numerically compared based on the initial typical impeller and the numerical–experimental verification. The numerical comparison shows that the leading-edge shape has a strong influence on the stalled flow pattern, velocity, pressure, turbulence kinetic energy, and flow-induced noise inside impellers. The blunt and sharp leading-edge impellers had a similar internal pattern; the ellipse and round leading-edge impellers were also similar in the internal flow-field. Pressure pulsation analysis showed more obvious differences among these impellers. The main frequency and the pulsation peak–peak values were completely different because of the slight leading-edge shape differences. It revealed the impact of leading-edge geometry on the transient flow-field change under the same incidence angle conditions. It also provided reference for influencing or controlling the rotating stall by blade profile design.
Highlights
When designing a pump impeller, two main targets need special considerations
Computational fluid dynamics (CFD) method was used for flow simulation
Computational fluid dynamics (CFD) method was used for predicting the flow field in centrifugal pump impellers with different leading-edge shapes
Summary
When designing a pump impeller, two main targets need special considerations. Firstly, operation efficiency at design load is important. Flow inside pump impeller under off-design conditions are treated as uncontrollable. The internal flow becomes complex at off-design load, especially at partial-load, with noise, vibration, and other undesirable phenomena. These phenomena would affectand theother stability and security of the pump off-design load, especially[6,7]. From design load to partial load, the incidence angle becomes higher and higher causes causes undesirable flow on the blade suction side [8]. Small-scale flow separationflow occurs on the blade suction sideblade [9]. Passage blockage happens brings both the inlet and outlet of the impeller.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: 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.