Closure to “Discussions of ‘A Theoretical Study on Air Bubble Motion in a Centrifugal Pump Impeller’” (1980, ASME J. Fluids Eng., 102, p. 454)

1980 ◽  
Vol 102 (4) ◽  
pp. 454-455
Author(s):  
Kiyoshi Minemura ◽  
Mitsukiyo Murakami
1980 ◽  
Vol 102 (4) ◽  
pp. 446-453 ◽  
Author(s):  
Kiyoshi Minemura ◽  
Mitsukiyo Murakami

Equations of motion for air bubbles in a centrifugal pump impeller were obtained and solved numerically for a flow in a radial-flow-type impeller, and the results were compared with experiments. Governing factors for the bubble motion are the force due to the pressure gradient, the drag force due to the flow resistance of the surrounding liquid, and the inertia force due to virtual mass of the liquid. If the bubble diameter is reduced continuously, the effect of the inertia force is also reduced and trajectories of the air bubbles approach more and more to the path of the flowing water.


2016 ◽  
Vol 10 (4) ◽  
pp. 215 ◽  
Author(s):  
Ioannis Kassanos ◽  
Marios Chrysovergis ◽  
John Anagnostopoulos ◽  
George Charalampopoulos ◽  
Stamelos Rokas ◽  
...  

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 311
Author(s):  
Renfei Kuang ◽  
Xiaoping Chen ◽  
Zhiming Zhang ◽  
Zuchao Zhu ◽  
Yu Li

This paper presents a large eddy simulation of a centrifugal pump impeller during a transient condition. The flow rate is sinusoidal and oscillates between 0.25Qd (Qd indicates design load) and 0.75Qd when the rotating speed is maintained. Research shows that in one period, the inlet flow rate will twice reach 0.5Qd, and among the impeller of one moment is a stall state, but the other is a non-stall state. In the process of flow development, the evolution of low-frequency pressure fluctuation shows an obviously sinusoidal form, whose frequency is insensitive to the monitoring position and equals to that of the flow rate. However, inside the impeller, the phase and amplitude in the stall passages lag behind more and are stronger than that in the non-stall passages. Meanwhile, the strongest region of the high-frequency pressure fluctuation appears in the stall passages at the transient rising stage. The second dominant frequency in stall passages is 2.5 times to that in non-stall passages. In addition, similar to the pressure fluctuation, the evolution of the low-frequency head shows a sinusoidal form, whose phase is lagging behind that by one-third of a period in the inlet flow rate.


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