Numerical investigation of the blade tip leakage vortex cavitation in a waterjet pump

Guo, Qiang; Huang, Xianbei; Qiu, Baoyun

doi:10.1016/j.oceaneng.2019.106170

Cited by 58 publications

(36 citation statements)

References 30 publications

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“…Accordingly, it is more important and reasonable to firstly ensure the capability of turbulence models (or to allow more turbulent vortical structures to be resolved on the URANS grids). In the future, it may be a good idea to combine the new MST model with other modified cavitation models (Ji et al , 2013; Guo et al , 2019) to further improve the prediction accuracy of more complex flow cases (e.g. cavitating TLV flows induced by different gap sizes, cavitating flows around a hydrofoil or in a pump).…”

Section: Resultsmentioning

confidence: 99%

Application of the MST turbulence model to predict the tip leakage vortex flows

Wang

et al. 2020

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Purpose Tip leakage vortex flow (TLV) is a common flow phenomenon in the axial-flow hydraulic machinery. High-efficiency simulation of TLV is still not an easy task because of the complex turbulent vortex-cavitation interactions. As an important basis of CFD, turbulence model directly affects the efficient computation of TLV. The purpose of this paper is to evaluate the newly developed MST turbulence model in predicting the TLV flows. Design/methodology/approach By using the MST turbulence model and the ZGB cavitation model, numerical simulations of the TLV generated by a NACA0009 hydrofoil were performed under the cavitation-free and cavitation conditions, and the results were compared with the available experimental data. Findings The important features of TLV are well captured by the MST-based simulation scheme, and the problem of under-predicting the cavitating TLV tube is well solved. Turbulent viscosity is reasonably adjusted in the TLV core regions, and the LES-like mode is activated, which is beneficial to obtain more turbulent information on the same URANS grids. The requirements of grid size and time step of the MST model are much lower than that of the LES method, thereby weighing a good balance between the simulation accuracy and computation cost. Originality/value The MST turbulence model is suitable for the high-efficiency simulation of the TLV flows, which can lay a good foundation for efficient engineering computations of the cavitating TLV in the axial-flow hydraulic machinery.

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Section: Resultsmentioning

confidence: 99%

Application of the MST turbulence model to predict the tip leakage vortex flows

Wang

et al. 2020

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“…However, it creates a problem due to the presence of tip clearance between the blade rim and the impeller shroud, which causes very large pressure gradient along the blade rim and generates tip leakage flow (TLF) and tip leakage vortex (TLV) in the impeller flow channels. [5][6][7] When mixed-flow pump operates at the design flow rate, the TLF and TLV are stable and approximately account for 15% of the total energy losses in impeller 6 as shown by Liu et al 7 Furthermore, it may also cause other performance problems as discussed later when the mixed-flow pump runs at flow rates different from design flow rate, especially near stall and stall condition. 8,9 For several decades, a great deal of research has been focused on developing correlations for tip leakage flow for various types of rotating fluid machinery [10][11][12] including axial compressors, 13 turbines, 14 and fan 15 etc.…”

Section: Introductionmentioning

confidence: 93%

Transient characteristics of internal flow fields of mixed-flow pump with different tip clearances under stall condition

Shi

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part A:

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This paper investigates the influence of different tip clearances on the transient characteristics of mixed-flow pump under stall condition. The instantaneous internal flow fields of mixed-flow pump with four tip clearances (0.2 mm, 0.5 mm, 0.8 mm and 1.1 mm) are explored by conducting unsteady time accurate simulations. Reynolds-averaged Navier-Stokes (RANS) equations are employed in the simulations and the results of computations are compared with experimental data. The results show that the pump head decreases by 22.1% and the pump efficiency drops by 13.9% at design flow condition when the impeller tip clearance increases from 0.2 mm to 1.1 mm. The swirling flow occurs in the inlet pipe of the mixed-flow pump with different tip clearances under stall condition, and the initial starting point of the swirling flow gets further away from the impeller inlet with increase in tip clearance because of increase in circumferential velocity and change in momentum of the tip leakage flow (TLF). The high turbulent eddy dissipation (TED) regions in the flow are attributed to the TLF, swirling flow, back flow and stall vortex, and their intensity are affected by the change in tip clearance. The oscillating trend of time domain distribution of TED enhances first and then decreases with increase in tip clearance and it exhibits a propagation feature under the effect of stall vortex, while most of the energy in the frequency domain remains concentrated in the low frequency part under stall condition.

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“…In the recent years, many studies have demonstrated that numerical simulations can accurately predict performances of the waterjet pump and its completely system [18,19]. Therefore, the commercial software ANSYS-CFX is used in this paper to simulate the three-dimensional flow within a waterjet pump under nonuniform inflow.…”

Section: Numerical Setupmentioning

confidence: 99%

Prediction and Evaluation of Waterjet Pump Performance under Nonuniform Inflow Using Parallel Compressor Theory

Cao

Zhu

2021

Water

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Parallel compressor theory (PCT) is commonly used to estimate effects of inlet distortion on compressor performance. As well as compressor, the actual inflow to pump is also nonuniform and unfavorable for performances. Nowadays, insufficient understanding of nonuniform inflow effects on pump performance restricts its development. Therefore, this paper applies PCT to predict external characteristics and evaluate internal flow instability of waterjet pump under nonuniform inflow. According to features of nonuniform inflow, the traditional PCT is modified and makes waterjet pump sub-divided into two circumferential tubes owning same performances but with different inlet velocity (representing nonuniform inflow). Above all, numerical simulation has been conducted to validated the applicability and accuracy of PCT in head prediction of waterjet pump under nonuniform inflow, since area-weighted sum of each tube head (i.e., theoretical pump head) is highly consistent with simulated result. Moreover, based on identifications of when and which tube occurs stall, PCT evaluates four stall behaviors of waterjet pump: partial deep stall, partial stall, pre-stall and full stall. Furthermore, different stall behavior generates different interactions between head variation of each tube, resulting in a multi-segment head curve under nonuniform inflow. The modified PCT with associated physical interpretations are expected to provide a sufficient understanding of nonuniform inflow effects on pump performances.

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Numerical investigation of the blade tip leakage vortex cavitation in a waterjet pump

Cited by 58 publications

References 30 publications

Application of the MST turbulence model to predict the tip leakage vortex flows

Application of the MST turbulence model to predict the tip leakage vortex flows

Transient characteristics of internal flow fields of mixed-flow pump with different tip clearances under stall condition

Prediction and Evaluation of Waterjet Pump Performance under Nonuniform Inflow Using Parallel Compressor Theory

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