A Theoretical Study of Fluid Forces on a Centrifugal Impeller Rotating and Whirling in a Vaned Diffuser

Tsujimoto, Yoshinobu; Acosta, A. J.; Yoshida, Yoshiki

doi:10.1299/kikaib.54.2266

Cited by 6 publications

(4 citation statements)

References 1 publication

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“…The effect of this gap: "Gap-A" on the precessing backshroud is different from that of the gap between the impeller outlet and guide vane, generally termed "Gap-B", on the whirling impeller. Fluid forces on the whirling impeller become more destabilizing with the smaller "Gap-B" (Tsujimoto et al [1988b]).…”

Section: Measurements Of the Flow Inmentioning

confidence: 99%

Measurements of the Flow in Backshroud/CasingClearance of Precessing Centrifugal Impeller

Yoshida

Tsujimoto

Ohashi

et al. 1997

International Journal of Rotating Machinery

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Detailed flow measurements have been made to clarify the unsteady flow in the backshroud/ casing clearance of a precessing centrifugal impeller. The unsteady pressure was integrated to obtain the fluid force moment on the precessing impeller shroud for various precessing frequencies. It was shown that the fluid force moment can become rotordynamically destabilizing for small forward precessing motion as originally found by Ohashi et al. The effects of leakage flow in the backshroud/casing clearance and a gap between impeller side plate and casing at the impeller outlet are clearly shown, and the discussions are also made based on the unsteady velocity and pressure measurements.

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Section: Measurements Of the Flow Inmentioning

confidence: 99%

Measurements of the Flow in Backshroud/CasingClearance of Precessing Centrifugal Impeller

Yoshida

Tsujimoto

Ohashi

et al. 1997

International Journal of Rotating Machinery

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“…The model al lowed eval uation of the pressure pe rturba tions in the impe ller discharge which compared well wi th th e ex perim ental measu rement s of these pert urbations. Tsuj imoto, et al [16], exa mined the two o r three dimensional character of the unsteady fl ow in order to establish the complex re lationship between the vOrlicity shed by th e im peller blades and the forces on the impe ll er.…”

Section: Shroud Orbitmentioning

confidence: 99%

Experimental Results for the Rotordynamic Characteristics of Leakage Flows in Centrifugal Pumps

Guinzburg

Brennen

Acosta

et al. 1994

Journal of Fluids Engineering

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In recent years, increasing attention has been given to fluid-structure interaction problems in turbomachines. The present research focuses on just one such fluid-structure interaction problem, namely, the role played by fluid forces in determining the rotordynamic stability and characteristics of a centrifugal pump. The emphasis of this study is to investigate the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. An experiment was designed to measure the rotordynamic shroud forces due to simulated leakage flows for different parameters such as flow rate, shroud clearance, face-seal clearance and eccentricity. The data demonstrate substantial rotordynamic effects and a destabilizing tangential force for small positive whirl frequency ratios; this force decreased with increasing flow rate. The rotordynamic forces appear to be inversely proportional to the clearance and change significantly with the flow rate. Two sets of data taken at different eccentricities yielded quite similar nondimensional rotordynamic forces indicating that the experiments lie within the linear regime of eccentricity.

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“…Consequently, the fluid force acting on rotor system is becoming significant, which could be one of the causes of the serious shaft vibration. At low flow rates, rotating stall phenomena occurring in impeller and/or diffuser are frequently regarded as one cause of major fluctuating radial thrust [1,2]. Therefore, in order to ensure the reliability of pumps in wide flow rate range, it is important to understand and predict the characteristics of radial thrust fluctuation due to rotating stall at the design stage.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of radial thrust fluctuation caused by diffuser rotating stall in a centrifugal pump

Takamine

Watanabe

2022

J. Phys.: Conf. Ser.

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In this study, in order to understand the relation between the diffuser rotating stall and the fluctuating radial thrust, unsteady RANS simulation of a centrifugal pump was carried out. The rotating stall with single stall cell was qualitatively reproduced though the propagation speed was smaller than the experiment. The pressure amplitude caused by the rotating stall was comparable to the measured one, and the tendency that the propagation speed increases as the flow rate increases agreed with experiment. The radial thrust fluctuation due to the rotating stall was well evaluated by the simulation, and a considerable difference of phase angle between the stall cell position and the working direction of radial thrust was detected, which also agreed with experiment. On the basis of simulation result, the reason is found to be that the radial force acting on the impeller external wall at the liner ring section due to stall cell was not very small but comparable to that acting on the impeller blade and outer wall, while their working directions were roughly 100° different. This suggests that considering the leakage flow in numerical simulation is important to accurately predict the radial forces generated by rotating stall.

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A Theoretical Study of Fluid Forces on a Centrifugal Impeller Rotating and Whirling in a Vaned Diffuser

Cited by 6 publications

References 1 publication

Measurements of the Flow in Backshroud/CasingClearance of Precessing Centrifugal Impeller

Measurements of the Flow in Backshroud/CasingClearance of Precessing Centrifugal Impeller

Experimental Results for the Rotordynamic Characteristics of Leakage Flows in Centrifugal Pumps

Numerical investigation of radial thrust fluctuation caused by diffuser rotating stall in a centrifugal pump

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