Prediction of Bubble Behavior in Centrifugal Pump by Using Cavitating Flow Simulation with Bubble Flow Model

Fukaya, Masashi; Tamura, Yoshiaki; Matsumoto, Yoichiro; Okamura, Tomoyoshi; Manabe, Akira

doi:10.1299/jsmemecjo.2004.2.0_343

Cited by 6 publications

(12 citation statements)

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“…The cavitation phenomena observed in hydraulic turbomachineries, such as axial flow pumps [8][9], inducer pump [10], and draft tube of Francis turbine [11], were analyzed by using a numerical simulation of the fluid dynamics. The cavitation performance or the region where the cavitation occurred was predicted by using numerical simulation.…”

Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamics of Cavitating Flow in Mixed Flow Pump with Closed Type Impeller

Kobayashi

Chiba²

2010

International Journal of Fluid Machinery and Systems

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LES(Large Eddy Simulation) with a cavitation model was performed to calculate an unsteady flow for a mixed flow pump with a closed type impeller. First, the comparison between the numerical and experimental results was done to evaluate a computational accuracy. Second, the torque acting on the blade was calculated by simulation to investigate how the cavitation caused the fluctuation of torque. The absolute pressure around the leading edge on the suction side of blade surface had positive impulsive peaks in both the numerical and experimental results. The simulation showed that those peaks were caused by the cavitaion which contracted and vanished around the leading edge. The absolute pressure was predicted by simulation with -10% error. The absolute pressure around the trailing edge on the suction side of blade surface had no impulsive peaks in both the numerical and experimental results, because the absolute pressure was 100 times higher than the saturated vapor pressure. The simulation results showed that the cavitation was generated around the throat, then contracted and finally vanished. The simulated pump had five throats and cavitation behaviors such as contraction and vanishing around five throats were different from each other. For instance, the cavitations around those five throats were not vanished at the same time. When the cavitation was contracted and finally vanished, the absolute pressure on the blade surface was increased. When the cavitation was contracted around the throat located on the pressure side of blade surface, the pressure became high on the pressure side of blade surface. It caused the 1.4 times higher impulsive peak in the torque than the averaged value. On the other hand, when the cavitation was contracted around the throat located on the suction side of blade surface, the pressure became high on the suction side of blade surface. It caused the 0.4 times lower impulsive peak in the torque than the averaged value. The cavitation around the throat caused the large fluctuation in torque acting on the blade.

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Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamics of Cavitating Flow in Mixed Flow Pump with Closed Type Impeller

Kobayashi

Chiba²

2010

International Journal of Fluid Machinery and Systems

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“…The governing equations are described in generalized coordinates as follows (9) (10) . The momentum conservation equation of bubble flow is In Eq.…”

Section: Governing Equationsmentioning

confidence: 99%

“…Microscopic bubble motion in the rotating flow of pumps has been numerically simulated with the "bubble flow model" (7)- (10) , which is a representative model for the numerical simulation of cavitating flow. The Rayleigh-Plesset equation (11) describing volumetric bubble motion is calculated in the flow field.…”

Section: Introductionmentioning

confidence: 99%

“…The predicted high-impact-load area corresponded to the observed erosion area on the impeller blade. We developed a simulation code with the bubble flow model, in which not only volumetric bubble motion but also transitional bubble motion was modeled, and the distribution of bubble nuclei in the cavitating flow was also taken into account (10) (13) . The high degree of prediction accuracy for cavitation erosion is promising since the physical phenomenon of cavitating flow is modeled in detail.…”

Section: Introductionmentioning

confidence: 99%

“…In the present study, the cavitation erosion area on the impeller blade surface of a centrifugal pump was predicted by using the simulation code we developed (10) (13) . We propose a numerical measure based on the bubble pressure and the bubble number density for estimating cavitation intensity.…”

Section: Introductionmentioning

confidence: 99%

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Prediction of Cavitation Intensity and Erosion Area in Centrifugal Pump by Using Cavitating Flow Simulation with Bubble Flow Model

Fukaya

Tamura

Matsumoto

2010

JFST

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We developed a numerical simulation code and a method of estimation for predicting the cavitation erosion in pumps. Cavitation erosion is closely related to cavitation intensity based on bubble dynamics. A "bubble flow model" simulates detailed bubble behavior in a cavitating flow. Cavitation intensity was estimated by analyzing the bubble pressure and bubble nuclei distribution in a centrifugal pump. We simulated the impulsive bubble pressure that varied in microseconds. The impulsive pressure was considered to be related to actual bubble collapse, which caused cavitation erosion. The erosion area was experimentally detected using a paint method. The predicted high cavitation intensity area agreed well with the experimental erosion area, since the predicted and experimental areas were both located between the shroud and mid-point of the blade near the leading edge. Our code was thus effective for estimating the cavitation intensity and predicting the erosion area around the impeller of a centrifugal pump.

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Multiscale Analysis on Cavitating Flow

Matsumoto

Okita

2011

6th AIAA Theoretical Fluid Mechanics Conference

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Cavitating flow is consisted of various scale phenomena such as each bubble motion and continuum bubbly flow. It is required to take those phenomena into account and to simulate those flows combining detail each bubble motion and wave phenomena in the cavitating bubbly flow. Reduced-order models are introduced to taken into account the compressibility of liquid and the internal phenomena of bubbles. The nonlinear behavior of the spherically symmetric bubble cloud is numerically investigated at various frequency and pressure amplitude conditions. As the result, when the amplitude of the pressure fluctuation is high enough to generate nonlinear waveform which has much higher harmonics components inside the cloud, the pressure wave strongly focuses at the cloud center. On the other hand, we apply our numerical simulation code with the bubble model for cavitating flows to predict the cavitation erosion in a centrifugal pump. The predicted high cavitation intensity area, which is estimated by analyzing the bubble pressure and bubble nuclei distribution in the flow, agrees well with the experimental erosion area.

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Prediction of Bubble Behavior in Centrifugal Pump by Using Cavitating Flow Simulation with Bubble Flow Model

Cited by 6 publications

References 0 publications

Computational Fluid Dynamics of Cavitating Flow in Mixed Flow Pump with Closed Type Impeller

Computational Fluid Dynamics of Cavitating Flow in Mixed Flow Pump with Closed Type Impeller

Prediction of Cavitation Intensity and Erosion Area in Centrifugal Pump by Using Cavitating Flow Simulation with Bubble Flow Model

Multiscale Analysis on Cavitating Flow

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