Numerical simulation of fluid added mass effect on a francis turbine runner

Liang, Quanwei; Rodríguez, Cristian; Egusquiza, Eduard; Escaler, Xavier; Farhat, Mohamed; Avellan, François

doi:10.1016/j.compfluid.2006.08.007

Cited by 109 publications

(92 citation statements)

References 20 publications

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“…One can see that both damping and polar inertia increases for off-nominal speed and with frequency. Recent research by Liang et al [18], and Rodriguez et al [19] has…”

Section: Discussionmentioning

confidence: 99%

“…The polar inertia of the mechanical system is J P = 1.57 Nms 2 , the damping is C = 0 Nms, and the stiffness is K = 49000 Nm. In Figure 7 the reduced eigenfrequencies (18) and in Figure 8 the damping ratio (19) due to the flow for such a fluid-mechanical system are presented and the influence of the different coefficients is illustrated. Relative torque (Nm/rad) Figure 4: Identification of the coefficients of (17), together with a curve-fitted function (rotational speed is 52 rad/s).…”

Section: Resultsmentioning

confidence: 99%

“…However, the results were not used in rotordynamical analysis. Liang et al [18] carried out finiteelement fluid-structure interactions of a turbine runner in still water and showed a reduction of the nonrotating eigenfrequencies compared to a runner in vacuum. The result had good agreement with the experimental results presented by Rodriguez et al [19].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical Estimation of Torsional Dynamic Coefficients of a Hydraulic Turbine

Karlsson¹,

Nilsson

Aidanpää

2009

International Journal of Rotating Machinery

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The rotordynamic behavior of a hydraulic turbine is influenced by fluid-rotor interactions at the turbine runner. In this paper computational fluid dynamics (CFDs) are used to numerically predict the torsional dynamic coefficients due to added polar inertia, damping, and stiffness of a Kaplan turbine runner. The simulations are carried out for three operating conditions, one at about 35% load, one at about 60% load (near best efficiency), and one at about 70% load. The runner rotational speed is perturbed with a sinusoidal function with different frequencies in order to estimate the coefficients of added polar inertia and damping. It is shown that the added coefficients are dependent of the load and the oscillation frequency of the runner. This affect the system's eigenfrequencies and damping. The eigenfrequency is reduced with up to 65% compared to the eigenfrequency of the mechanical system without the fluid interaction. The contribution to the damping ratio varies between 30-80% depending on the load. Hence, it is important to consider these added coefficients while carrying out dynamic analysis of the mechanical system.

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“…One can see that both damping and polar inertia increases for off-nominal speed and with frequency. Recent research by Liang et al [18], and Rodriguez et al [19] has…”

Section: Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical Estimation of Torsional Dynamic Coefficients of a Hydraulic Turbine

Karlsson¹,

Nilsson

Aidanpää

2009

International Journal of Rotating Machinery

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“…Given the previous experience with the sensitivity of the element shape, the mesh density and the effects of the added mass of water [6][7][8][9], the runner was modeled with 680,772 elements and 856,551 nodes. To consider the effect of the water, the runner was surrounded by the fluid domain.…”

Section: Dynamics Of the Runner Structurementioning

confidence: 99%

Failure investigation of a large pump-turbine runner

Egusquiza

Valero

Huang

et al. 2012

Engineering Failure Analysis

159

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a b s t r a c tA failure investigation was conducted on a high-pressure machine with a large pump-turbine runner that was 2.9 m in diameter and had a maximum discharge rate of 32 m 3 /s.A part of the runner broke off during operation. This released a piece of the crown, which went through the machine, causing further damage. An analysis of the broken runner revealed a fatigue problem, so the dynamic/vibratory behavior of the runner during machine operation was investigated to determine the cause.First, the excitation forces acting on the runner during operation were studied. The main excitation in pump-turbines is generated by the interference between the rotating blades and the stationary vanes, known as a rotor-stator interaction (RSI), which produces large pressure pulsations. The amplitude of the pressure pulsations was measured in the prototype using pressure transducers.Second, the modal response of the runner structure was analyzed. A finite element (FEM) model of the runner was developed and the main natural frequencies and associated mode shapes were identified.A dynamic analysis was then performed to determine the runner response. A harmonic excitation simulating the pressure pulsation of the RSI was applied to the numerical model of the runner. The results showed a large stress concentration in the T-joint between the blade and crown where the crack originated. Finally, the possible causes of the damage are discussed.

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“…From the equation [3], the nodal diameter equals to the harmonic index in only some cases, and the solution of a given harmonic index may contain more than one mode with differe nt nodal diameters.…”

Section: Introductionmentioning

confidence: 99%

Modal behavior of a reduced scale pump turbine impeller. Part II: Numerical simulation

Valero¹,

Huang²,

Egusquiza³

et al. 2010

IOP Conf. Ser.: Earth Environ. Sci.

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Abstract.A numerical simulation has been carried out to analyze the modal behavior of a reduced scale pump-turbine impeller. The simulation has been done using FEM method, in air and in water. The same boundary conditions than in the experiment were considered: free body in air and free body submerged in a reservoir of water. A sensitivity analysis to determine the influence of the number of elements was done. The influence of the input parameters was also taken into account. Finally, a mesh with 165000 elements for the impeller in air and of 508676 for the impeller in water was used. The results obtained with the simulation have been compared with the experimental ones (paper 1). Both the natural frequency values and the mode-shapes were compared. The numerical results showed small deviation from experiment in the first modes in modes with low modal density. In some coupled modes been found. With the updated model the mode-shapes have been analyzed. Some modes with high modal density have been found. As indicated in the experiment, the effect of the added mass reduces the natural frequencies and also changes the characteristics of the coupled modes.

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Numerical simulation of fluid added mass effect on a francis turbine runner

Cited by 109 publications

References 20 publications

Numerical Estimation of Torsional Dynamic Coefficients of a Hydraulic Turbine

Numerical Estimation of Torsional Dynamic Coefficients of a Hydraulic Turbine

Failure investigation of a large pump-turbine runner

Modal behavior of a reduced scale pump turbine impeller. Part II: Numerical simulation

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