Fluid-induced rotordynamic forces and instabilities

Brennen, Christopher E.; Acosta, A. J.

doi:10.1002/stc.145

Cited by 20 publications

(10 citation statements)

References 20 publications

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“…Therefore, the flow field simulation not only considered the impeller rotation but the whirl motion as well. The impeller whirl model [42] was introduced as shown in Fig. 2, where e is an eccentricity of the mixed-flow pump impeller and adjusted as 0 mm, 0.3 mm and 0.5 mm.…”

Section: Impeller Whirling Motion Modelmentioning

confidence: 99%

Numerical investigation of internal flow characteristics in a mixed-flow pump with eccentric impeller

Shi

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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In order to study the internal flow fields of mixed-flow pump with eccentric impeller, the numerical simulation and experiment have been conducted based on the dynamic sliding multi-region method. During simulation, the impeller domain has been separated by three sub-domains to apply the whirl effect. The pressure, turbulent kinetic dissipation and streamline distribution in the tip clearance were analyzed. The results show that the energy performance of calculation is basically consistent with the experimental results, which indicates the accuracy of energy performance prediction. The efficiency and head at the design flow condition drop about 20% and 11%, respectively, when e = 0.5 mm. The circumferential pressure distribution of impeller inlet and outlet is influenced greatly by the eccentric impeller, but the middle part of impeller suffered little effects as a result of the rotation effect of impeller. When the impeller is eccentric, the tip leakage flow and tip leakage vortex (TLV) are restrained at small tip clearance but enhance at large tip clearance. The angle between the TLV core and blade rim also increases at large tip clearance but decreases at small tip clearance. More energy has dissipated in the first half part of impeller channel within tip region, and the impacting depth increases with the increase in eccentricity, which affect the inlet flow fields of impeller at large eccentricity. The turbulent kinetic dissipation and hydraulic losses increase with the increase in eccentricity, which is the main factor for the decrease in pump efficiency.

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Section: Impeller Whirling Motion Modelmentioning

confidence: 99%

Numerical investigation of internal flow characteristics in a mixed-flow pump with eccentric impeller

Shi

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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“…In further studies, it is intended to apply a twolayer (hybrid) control, 10,15,16 where the feedforward technique actuates to improve the overall performance of a stabilizing robust feedback loop 4,17 to deal, specifically, with the oil whip limitation described in the literature. 6,18 2 | NOTATION A particular notation is defined to provide a clear distinction between different coordinates, time, and frequency domains.…”

Section: Introductionmentioning

confidence: 99%

“…The tests are performed in distinct operation conditions to accentuate distinct effects to demonstrate the applicability potential. In further studies, it is intended to apply a two‐layer (hybrid) control, where the feedforward technique actuates to improve the overall performance of a stabilizing robust feedback loop to deal, specifically, with the oil whip limitation described in the literature …”

Section: Introductionmentioning

confidence: 99%

Feedforward Rotor Fault Compensation

Cavalca

Markert

2020

Struct Control Health Monit

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When damaged, it is not unusual to observe nonlinear responses in previously linear structures. Specifically, in rotating machinery context, unbalance, misalignment, bearing, and shaft damage occur during operation, and their responses arise as a combination of multiple modes and harmonics. These vibration effects are undesirable and, besides compromising the system performance, can propagate or generate further faults. In practice, the machine cannot be simply stopped for repairs, and a method for provisory attenuating such problems is desirable. The fault effects can be approximated by a set of loads distributed along the healthy rotor linear model approximation. Intuitively, one can also estimate counteractive forces to mitigate the fault symptoms. Therefore, this work proposes a simple feedforward approach to detect and compensate fault effects at multiple harmonics in rotors. The compensating force is calculated to minimize the least square modal difference between healthy and faulty rotor. A test rig is operated in distinct conditions to demonstrate and validate the method highlighting different fault symptoms (unbalance, misalignment, and shaft bow).

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“…This effect was known as the Lomakin effect [17]. The effect was well studied both experimentally [18,19] and numerically [20,21]. The main goal of the paper was to study the influence of the wear ring clearance gap on the transient flow in the pump.…”

Section: Introductionmentioning

confidence: 99%

Investigation into Transient Flow in a Centrifugal Pump with Wear Ring Clearance Variation

Liu

Ding

Dai

et al. 2014

Advances in Mechanical Engineering

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The leakage flow paths in the sidewall gaps of centrifugal pumps are of significant importance for numbers of effects. The paper is concerned with the transient flow in the leakage flow paths with wear ring clearance variation. For this purpose, numerical simulations of the whole pump were carried out. The grid dependence and yplus check were performed first. Additionally, experimental data of performance characteristic and pressure fluctuation inside the sidewall gap was used to validate the numerical results. The transient velocity fields inside the sidewall gaps during one blade passage period were simulated. And the leakage through the wear ring gap was obtained for all operating points investigated. To have a better idea of attenuation and propagation of pressure inside the sidewall gap, the unsteady pressure distributions in the gap were calculated. Additionally, the surfaces of the impeller were divided into four parts. The fluid force on each part was expressed as a percentage of the total radial force. Through comparing the flow fields, the pressure distributions, and the radial force between the pumps with different wear ring clearances, the effects of the wear ring clearance were discussed in detail. The results can be used to guide the optimum design of the pump sidewall gaps.

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Fluid-induced rotordynamic forces and instabilities

Cited by 20 publications

References 20 publications

Numerical investigation of internal flow characteristics in a mixed-flow pump with eccentric impeller

Numerical investigation of internal flow characteristics in a mixed-flow pump with eccentric impeller

Feedforward Rotor Fault Compensation

Investigation into Transient Flow in a Centrifugal Pump with Wear Ring Clearance Variation

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