Lateral Fluid Forces on Whirling Centrifugal Impeller (1st Report: Theory)

Shoji, Hidenobu; Ohashi, Hideo

doi:10.1115/1.3242647

Cited by 14 publications

(5 citation statements)

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“…1. Rotordynamic fluid forces on a free impeller basically have no destabilizing effect except at Corresponding author. low flow rate (Ohashi et al [1984] and Shoji et al [1987]).…”

Section: Introductionmentioning

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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“…1. Rotordynamic fluid forces on a free impeller basically have no destabilizing effect except at Corresponding author. low flow rate (Ohashi et al [1984] and Shoji et al [1987]).…”

Section: Introductionmentioning

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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“…Li Wei [9], based on RNG k-ε, designed a model that simulates the internal flow field of the mixed-flow pump under the eccentricity of 0 mm, 0.3 mm, and 0.5 mm, and revealed the flow characteristics of the non-uniform tip clearance flow field of the mixed-flow pump. Shoji [10] and Adkins [11] respectively analyzed the fluid excitation force in the centrifugal impeller vortex by using the potential flow theory and pure dynamics models. The research shows that the fluid excitation force acting on the impeller outlet is dominant when the vortex rate is relatively low and studied the vortex of the open centrifugal impeller.…”

Section: Introductionmentioning

confidence: 99%

Vortex Dynamics Analysis of Internal Flow Field of Mixed-Flow Pump under Alford Effect

Wei

et al. 2021

Water

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A multi-region dynamic slip method was established to study the internal flow characteristics of the mixed-flow pump under the Alford effect. The ANSYS Fluent software and the standard k-ε two-equation model were used to numerically predict the mixed-flow pump’s external characteristics and analyze the forces on the impeller and guide vane internal vortex structure and non-uniform tip gap of the mixed-flow pump at different eccentric distances. The research results show that the external characteristic results of the numerical calculation are consistent with the experimental measurement. The head error of the design flow operating point is about 5%, and the efficiency error is no more than 3%, indicating the high accuracy of numerical calculation. Eccentricity has a significant influence on the flow field in the tip area of the mixed-flow pump impeller, the distribution of vortex core in the impeller presents obvious asymmetry, the strength and distribution area of the vortex core in the small gap area of the tip increase obviously, which aggravates the flow instability and increases the energy loss. With the increase of eccentricity, the strength and number of vortex core structures in the guide vane also increase significantly, and obvious flow separation occurs near the inlet of the guide vane suction surface on the eccentric side of the impeller. The circumferential distribution of L1 and L2 values represents the friction pressure gap in the eccentric state, and the eccentricity has a more noticeable effect on L1 and L2 values at the small gap; With the increase of eccentricity, the values of vorticity moment components L1 and L2 increase, and the Alford moment on the impeller increases. The leading-edge region of the blade is the main part affected by the unstable torque of the flow field. With the increase of eccentricity, the impact degree of tip leakage flow deepens, and the change of the tip surface pressure is the most obvious. The impact area of tip leakage flow is mainly concentrated in the first half of the impeller channel, which has an impact on the blade inlet flow field but has little impact on the blade outlet flow field.

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“…The problems for the front and back seal forces have been solved by the long term thorough investigations into the liquid dynamic annular seals. Researches for the forces on the impeller periphery have been done by several scholars and progresses have been made so far, since initiated in the 1980's [1][2][3][4][5][6][7]. As for the problem of forces on impeller front shroud, Childs [8] in 1989 first investigated the fluid-structure interaction forces on a centered impeller front shroud by introducing the bulk-flow model into the procedure for the first time.…”

Section: Introductionmentioning

confidence: 99%

“…The pressure and path velocity fluctuate more drastically in the presence of the eccentricity. The circumferential velocity goes up significantly overall along the circumference and the flow path (5). The uneven pressure distribution of the flow on the front shroud due to the impeller eccentricity along the circumference and the pressure gradient along the flow path can result in an eccentric force and an offset moment, which are the sources of rotor vibrations.246 Management, Manufacturing and Materials Engineering 092300410037).…”

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confidence: 99%

The Influences of Impeller Eccentricity on Front Leakage Flow

Zheng

Wang

Zhang

2012

AMR

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A numerical analysis on the steady-state front leakage flow of an eccentric impeller is done based on a bulk-flow model. A set of nonlinear partial differential governing equations is derived on a control volume from the flow. The SIMPLE algorithm is used to develop the computational procedure for solving the equations. A MATLAB computer program in accordance with the computational procedure is written to conduct the numerical calculations. Numerical results are represented with the diagrams of pressure and velocity distribution of the flow. The influences of the impeller eccentricity on the flow are examined in a limited range of engineering practice. Conclusions are reached that the impeller eccentricity has substantial effects on the pressure and velocity distributions of the front leakage flow.

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Lateral Fluid Forces on Whirling Centrifugal Impeller (1st Report: Theory)

Cited by 14 publications

References 0 publications

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

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

Vortex Dynamics Analysis of Internal Flow Field of Mixed-Flow Pump under Alford Effect

The Influences of Impeller Eccentricity on Front Leakage Flow

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