DDES analysis of the unsteady wake flow and its evolution of a centrifugal pump

Zhang, Ning; Liu, Xiaokai; Gao, Bo; Xia, Bin

doi:10.1016/j.renene.2019.04.023

Cited by 85 publications

(44 citation statements)

References 19 publications

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“…Consequently, the pressure pulsation and turbulence kinematic energy are both weak, which ensures the main shaft work in stable operation with relatively low vibration and stress levels. Given the part-load conditions, the RSI is strong when the impeller blade sweeps over the volute tongue, and it brings a series of unstable flow phenomena, such as the flow cutting and impingement in the nearby region of tongue, which has been observed by PIV measuring [10]. The inner unstable flow finally causes high fluctuation of radial forces of the impeller and significant vibration of the main shaft.…”

Section: Discussionmentioning

confidence: 99%

“…One possible explanation is that the high flow suppresses the separation degree of fluid media, and it is the flow rate factor rather than pump structure that dominant the entire flow process. However, illustrating the flow induced mechanism of the rotor vibration is a very complex task, and a more accurate CFD computation, such as detached eddy simulation [10] and some new comparative analysis methods, may be needed in the further research.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, a proportional damping was applied onto the entire finite element analysis model. This implies that the system damping matrix [C] in Equation (6) is approximately treated as the linear combination of mass matrix [M] and the stiffness matrix [K], as expressed in the Equation (10) […”

Section: Solution Setup and Damping Coefficient Selectionmentioning

confidence: 99%

“…Similar pulsation tendency is also fund in the hydraulic radial force on the impeller, because the hydraulic force mainly depends on the integration of pressure on the impeller surfaces. In addition, there are also other obvious frequency components rather than f BPF or multiple f n , which are stimulated by a serious complex unsteady flow behaviors, such as the jet-wake pattern along the blade extension direction, the flow impact on the tongue, and the flow separation on the blade suction surface [10][11][12]. The above behaviors usually become more evident under off-design conditions and would take much greater risks for the operation of centrifugal pump [13,14].…”

Section: Introductionmentioning

confidence: 99%

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CFD-Rotordynamics Sequential Coupling Simulation Approach for the Flow-Induced Vibration of Rotor System in Centrifugal Pump

Zhang

You

et al. 2020

Applied Sciences

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Featured Application: The numerical approach in this article can provide abundant information about the flow induced vibration of the pump rotor and may offer theoretical guidance to the design of reducing vibration and safety monitoring of centrifugal pumps.Abstract: Vibration of the rotor system is closely related with the operation stability of centrifugal pump, and it is inevitably induced by the unsteady inner flow. An unsteady computational fluid dynamics model coupling with a rotordynamics model was presented, and the corresponding numerical calculation program, including a self-designed rotordynamics code, was developed on the commercial package ANSYS Workbench. The validity of the numerical calculation model was verified by a hydraulic performance and vibration test based on an industrial centrifugal pump. The hydraulic radial forces on impeller, pressure pulsation, deformation, and vibration of the main shaft under nine different flow rates were systematically investigated and explained preliminarily from the view of inner unstable flow. Results show that the blade passing frequency is the dominant frequency in the fluctuation of the above dynamical behaviors, which is closely related to the rotor-stator interaction between the impeller and volute casing. This study built the connection between internal fluid flow in the centrifugal pump and the vibration of its external rotor structure, and may provide theoretical references for the design of vibration-reducing and safety monitoring strategies design of centrifugal pumps.3 of 33 former works, the first and foremost improvement of this work is the application of rotordynamics in the CSD, where the bearing damping matrix and gyroscopic matrix have been added to the general dynamic equation. With this advantage, the above new approach is able to provide a wealth shaft oscillation information including vibration velocity and shaft centerline orbit, with both the unsteady hydraulic force on the impeller and the rotor dynamic properties in consideration.In this article, an industrial split-case double suction centrifugal pump was chosen for study, and the unsteady flow as well as rotor assembly vibration behaviors under different operation conditions were investigated. The remaining of this article was organized as follows. In Section 2, the mathematical model and its overall frame are presented. Section 3 describes the computation details and experiment setup for a research case. Sections 4 and 5 are the analysis and discussion for the numerical and experimental results, followed by the conclusions in Section 6. Sequential Coupling Model Hypothesis and SimplificationThis study constructs the CFD-rotordynamics sequential coupling numerical model of centrifugal pump mainly based on following hypotheses and simplifications:(1) The coupling between flow field and rotordynamics belongs to one-way coupling. It means that only influences of flow induced exciting force on the vibration behavior of the rotor system were considered, but interferences of the deformati...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Solution Setup and Damping Coefficient Selectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

CFD-Rotordynamics Sequential Coupling Simulation Approach for the Flow-Induced Vibration of Rotor System in Centrifugal Pump

Zhang

You

et al. 2020

Applied Sciences

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“…The increase of the head and efficiency is due to the gentler flow of fluid from the STTE trailing edge. A typical wake-jet structure exists in the outlet area of the impeller, which causes the main energy loss of the centrifugal pump [49]. By modifying the trailing edge shape, the structure and frequency of the shedding vortex at the impeller exit are changed, and the development of the wake-jet structure is suppressed.…”

Section: Performance Analysis Of Two Test Pumpsmentioning

confidence: 99%

The Role of Blade Sinusoidal Tubercle Trailing Edge in a Centrifugal Pump with Low Specific Speed

Jia

et al. 2019

Processes

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Pressure pulsations may cause high-amplitude vibrations during the process of a centrifugal pump. The trailing edge shape of the blade has a critical influence on the pump’s pressure fluctuation and hydraulic characterization. In this paper, inspired by the humpback whale flipper, the authors research the impact of applying the sinusoidal tubercles to the blade suction side of the trailing edge. Numerical calculation and experiments are carried out to investigate the impact of the trailing edge shape on the pressure pulsations and performance of a centrifugal pump with low specific speed. Two designed impellers are tested, one is a sinusoidal tubercle trailing edge (STTE) impeller and the other is the original trailing edge (OTE) prototype. The detailed study indicates that the sinusoidal tubercle trailing edge (STTE) reduces pressure pulsation and enhances hydraulic performance. In the volute tongue region, the pressure pulsation amplitudes of STTE at fBPF decrease significantly. The STTE impeller also effectively changes the vortex structure and intensity in the blade trailing edge area. This investigation will be of great benefit to the optimal design of pumps.

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Effect of the staggered impeller on reducing unsteady pressure pulsations of a centrifugal pump

Jiang

Zhang

Liu

et al. 2021

Energy Science & Engineering

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The emitted noise and vibration induced by the unsteady flow of the centrifugal pump are always focused during its running, which is also associated with the high amplitude pressure pulsations. How to reduce pressure pulsations remains a crucial problem for the researcher considering low noise design of the centrifugal pump. In the current research, a special staggered impeller is proposed to reduce intense pressure pulsations of a centrifugal pump with n s = 69 based on alleviating rotor-stator interaction. The numerical simulation method is conducted to illustrate the influence of staggered impeller on the pump performance and pressure pulsations, and three typical flow rates (0.8Ф N -1.2Ф N ) are simulated. Resultsshow that the staggered impeller will lead to the pump head increasing, and at the design working condition, the increment reaches about 3% compared with the original impeller. Meanwhile, the pump efficiency is little affected by the staggered impeller, which is almost identical with the original impeller. From comparison of pressure spectra at 20 monitoring points around the impeller outlet, it is validated that the staggered impeller contributes significantly to decreasing pressure pulsations at the concerned working conditions. At the blade passing frequency, the averaged reduction of 20 points reaches 89% by using the staggered impeller at 1.0Ф N . The reduction reaches to 90%, 80% at 0.8Ф N , 1.2Ф N , respectively. Caused by the rib within the staggered impeller, the internal flow field in the blade channel will be affected. Finally, it is concluded that the proposed staggered impeller surely has a significant effect on alleviating intense pressure pulsation of the model pump and does not obviously alter the global performance of the pump, which is very promising during the low noise pump design considering its feasibility for manufacturing.

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DDES analysis of the unsteady wake flow and its evolution of a centrifugal pump

Cited by 85 publications

References 19 publications

CFD-Rotordynamics Sequential Coupling Simulation Approach for the Flow-Induced Vibration of Rotor System in Centrifugal Pump

CFD-Rotordynamics Sequential Coupling Simulation Approach for the Flow-Induced Vibration of Rotor System in Centrifugal Pump

The Role of Blade Sinusoidal Tubercle Trailing Edge in a Centrifugal Pump with Low Specific Speed

Effect of the staggered impeller on reducing unsteady pressure pulsations of a centrifugal pump

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