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| 1 | Experimental Study of the Pressure Fluctuations in a Pump Turbine at Large Partial Flow Conditions显示文摘Frequent shifts of output and operating mode require a pump turbine with excellent stability. Current researches show that large partial flow conditions in pump mode experience positive-slope phenomena with a large head drop. The pressure fluctuation at the positive slope is crucial to the pump turbine unit safety. The operating instabilities at large partial flow conditions for a pump turbine are analyzed. The hydraulic performance of a model pump turbine is tested with the pressure fluctuations measured at unstable operating points near a positive slope in the performance curve. The hydraulic performance tests show that there are two separated positive-slope regions for the pump turbine, with the flow discharge for the first positive slope from 0.85 to 0.91 times that at the maximum efficiency point. The amplitudes of the pressure fluctuations at these unstable large partial flow conditions near the first positive slope are much larger than those at stable operating condtions. A dominant frequency is measured at 0.2 times the impeller rotational frequency in the flow passage near the impeller exit, which is believed to be induced by the rotating stall in the flow passage of the wicket gates. The test results also show hysteresis with pressure fluctuations when the pump turbine is operated near the first positive slope. The hysteresis creates different pressure fluctuations for those operation points even though their flow rates and heads are similar respectively. The pressure fluctuation characteristics at large partial flow conditions obtained by the present study will be helpful for the safe operation of pumped storage units. | RAN Hongjuan LUO Xianwu ZHU Lei ZHANG Yao WANG Xin XU Hongyuan | 2012 | Chinese Journal of Mechanical Engineering2012，25，6： | 33 |
| 2 | Multi-objective optimization of a mixed-flow pump impeller using modified NSGA-II algorithm显示文摘In order to maintain a uniform distribution of pareto-front solutions, a modified NSGA-II algorithm coupled with a dynamic crowding distance(DCD) method is proposed for the multi-objective optimization of a mixed-flow pump impeller. With the pump meridional section fixed, ten variables along the shroud and hub are selected to control the blade load by using a three-dimensional inverse design method. Hydraulic efficiency, along with impeller head, is applied as an optimization objective; and a radial basis neural network(RBNN) is adopted to approximate the objective function with 82 training samples. Local sensitivity analysis shows that decision variables have different impacts on the optimization objectives. Instead of randomly selecting one solution to implement, a technique for ordering preferences by similarity to ideal solution(TOPSIS) is introduced to select the best compromise solution(BCS) from pareto-front sets. The proposed method is applied to optimize the baseline model, i.e. a mixed- flow waterjet pump whose specific speed is 508 min?1?m3s?1?m. The performance of the waterjet pump was experimentally tested. Compared with the baseline model, the optimized impeller has a better hydraulic efficiency of 92% as well as a higher impeller head at the design operation point. Furthermore, the off-design performance is improved with a wider highefficiency operation range. After optimization, velocity gradients on the suction surface are smoother and flow separations are eliminated at the blade inlet part. Thus, the authors believe the proposed method is helpful for optimizing the mixed-flow pumps. | HUANG RenFang LUO XianWu JI Bin WANG Peng YU An ZHAI ZhiHong ZHOU JiaJian | 2015 | Science China(Technological Sciences)2015，58，12： | 32 |
| 3 | Cavitation shedding dynamics around a hydrofoil simulated using a filter-based density corrected model显示文摘The unsteady turbulent cloud cavitation around a NACA66 hydrofoil was simulated using the filter-based density corrected model(FBDCM). The cloud cavitation was treated as a homogeneous liquid-vapor mixture and the effects of turbulent eddy viscosity were reduced in cavitation regions near the hydrofoil and in the wake. The numerical results(in terms of the vapor shedding structure and transient pressure pulsation due to cavitation evolution) agree well with the available experimental data, showing the validity of the FBDCM method. Furthermore, the interaction of vortex and cavitation was analyzed based on the vorticity transport equation, revealing that the cavitation evolution has a strong connection with vortex dynamics. A detailed analysis shows that the cavitation could promote the vortex production and flow unsteadiness by the dilatation and baroclinic torque terms in the vorticity transport equation. | YU An JI Bin HUANG RenFang ZHANG Yao ZHANG YuNing LUO XianWu | 2015 | Science China(Technological Sciences)2015，58，5： | 8 |
| 4 | Unstable flow characteristics in a pump-turbine simulated by a modified Partially-Averaged Navier-Stokes method显示文摘Positive slope characteristics are very important for the safe and stable operation of a pump-turbine. In this study, the unsteady flows in a pump-turbine at pump mode are investigated numerically. To predict the positive slope characteristics with an improved accuracy, a modified Partially-Averaged Navier-Stokes(MPANS) model is employed to capture the unstable physics in a pump-turbine. It is confirmed that the present numerical method predicts the positive slope characteristics in the pumpturbine fairly well compared with the experimental data. It is noted that at the drooping point of the performance curve(positive slope), there are three sets of rotating stall cells in the flow passages of both the guide vanes and stay vanes. In the guide vane region, the flow is completely shut off by the rotating stall, whereas in the stay vane region, the flow passage is partly blocked at the drooping point. The numerical results also reveal that the remarkable variation and high angle of attack(AOA) values upstream the leading edge of the guide vane contribute to the flow separation at the vane suction side and induce rotating stall in the flow passage within the positive slope region. Furthermore, the propagation of the rotating stall is depicted by both Eulerian and Lagrangian viewpoints: the rotating stall blocks the flow passage between two neighboring guide vanes and pushes the flow toward the leading edge of the subsequent guide vane. The rotating stall cell shifts along the rotational direction with a much lower frequency(0.146 f_n) compared with the runner rotational frequency, f_n. | YANG Dandan LUO XianWu LIU DeMin HUANG RenFang ZHU ZuChao | 2019 | Science China(Technological Sciences)2019，62，3： | 7 |
| 5 | Analysis of ventilated cavitation around a cylinder vehicle with nature cavitation using a new simulation method显示文摘In the present paper, a new simulation method is developed for unsteady cavitating flow with air ventilation,which is very useful for alleviating the pressure oscillation in hydroturbine draft tube and reducing the drag force on an underwater vehicle. Because the fluid includes three components, i.e., the water, vapor, and air, the interactions between water–air and water–vapor are treated by applying the level set method, and the effect of surface tension is taken into account in governing equations. Further, the phase change between the water and the vapor is modeled by a homogeneous model,where the effect of air injection is considered by applying the air volume fraction in the mass transport equation. For calibration, the cavitating flows around a cylinder vehicle were simulated using the proposed method, and the numerical results were compared with the experimental data at three different ventilation conditions. The good agreement of cavitation evolutions between the simulation and the experiment indicated that the proposed method was acceptable for the simulation of ventilated cavitating flows with nature cavitation and would be usable for various engineering applications.Moreover, the vorticity analysis depicts that the vortex is closely related to cavitation evolution, and air injection much changes the vorticity production in cavitating flow. It was also revealed that vorticities only occurred in regions with high vapor/air volume fraction and the vortex stretching term created the most vorticities. | An Yu Xianwu Luo Bin Ji | 2015 | Science Bulletin2015，60，21： | 5 |
| 6 | A miniature pump with a fluid dynamic bearing显示文摘This paper describes the development of a miniature pump having an impeller with an exit diameter of 24 mm supported with the motor rotor by a fluid dynamic bearing.Tests verify that the miniature pump is stable and quiet for rotational speeds larger than 4000 min-1.The three-dimensional turbulent flow in the entire pump flow passage and the laminar flow in the fluid dynamic bearing were then simulated numerically.The average pump performance was well predicted by the simulations.Both the tests and the simulations show that there is no obvious Reynolds effect for the miniature pump within the tested range of rotational speeds.The numerical results also show that the bearing capacity of the fluid dynamic bearing increases with the pump rotor rotational speed and the eccentricity ratio of the journal to the bushing.This pump is very compact,so it is a promising device for surgical use. | LUO XianWu JI Bin ZHUANG BaoTang ZHU Lei LU Li XU HongYuan | 2012 | Science China(Technological Sciences)2012，55，3： | 4 |
| 7 | Effects of operating condition on fish behavior and fish injury in an axial pump显示文摘In this study,fish behavior and fish injury at different operating conditions are investigated via numerical simulation to evaluate the fish-friendliness of an axial pump that comprises an inlet pipe,a rotor with six blades,a stator with eight vanes,and an outlet pipe.To precisely obtain the flow field when the fish passes through the axial pump,a hybrid large eddy simulation and immersed boundary method is adopted with the full consideration of the fluid-structure interaction comprehensively.The results indicate that the collision between the fish and the wall of flow components in the axial pump is concentrated near the inlet of the rotor,which results in the complexity of the fish trajectory,especially under the large flow rate condition.It is noted that the fish is likely to move in the reverse direction of the main flow after the impact with the rotor blade if the flow rate coefficient is too large,which increases the possibility of collision between the fish and the rotor blade.It is also indicated that the primary factor affecting the strike injury on the fish when it passes through the axial pump is the strike between the fish and the leading edge of the rotor blade.In addition,the strike injury becomes more significant as the flow rate coefficient increases.Furthermore,the results demonstrate that the fish may simultaneously suffer from strike,pressure,and shear stress injuries,once the collision between the fish and the wall of flow components occurs in the axial pump,thus aggravating the combined damage on the fish.Based on these results,it is recommended that hydraulic machinery should not be operated at large flow rates during fish migration from the view of fish-friendliness. | YANG DanDan ZHAO MingXiang SHEN Lian LUO XianWu | 2022 | Science China(Technological Sciences)2022，65，1： | 3 |
| 8 | REE Characteristics of a New Uranium Mineral from the Xianshi Uranium Deposit, South China显示文摘Objective Galuskin et al.(2011)firstly discovered that vorlanite(CaU^(6+/4+))O_4 is a rare Ca-rich mineral with a fluorite-type structure,which is isostructural with uraninite(U^(4+)O_2).Previous studies of the Xianshi granite-related uranium deposit reported that uraninite and pyrite are the major ore minerals whereas galena,clausthalite(PbSe),and pyrite are minor phases in the ores.A more detailed | LUO Jincheng HU Ruizhong BI Xianwu CHEN Youwei | 2018 | Acta Geologica Sinica(English Edition)2018，92，4： | 2 |
| 9 | Numerical study of unsteady cavitation on 2D NACA0015 hydrofoil using free/open source software显示文摘The free/open source software as OpenFOAM,Salome meshing and python language under Debian Linux system are evaluated to model unsteady cavitating turbulent flow around a NACA0015 hydrofoil. Based on the cavitation model proposed by Kunz and large eddy simulation(LES) method, we denote the benefits of free software and open source tools as an alternative to proprietary software of computational fluid mechanics, and provided a modified cavitation model to improve numerical accuracy.The simulation results of typical break-off cycle for cavitation shedding are compared to available experimental data, and validated using image processing to find percentage of similarities. The sheet cavity frequency of 7.752 Hz was obtained based on cavitation evolution and pressure fluctuations. The study gives relevant information for CFD software development in the future. | Victor Hidalgo Xianwu Luo Bin Ji Alvaro Aguinaga | 2014 | Chinese Science Bulletin2014，59，26： | 2 |
| 10 | Impeller inlet geometry effect on performance improvement for centrifugal pumps 显示文摘 | LUO Xianwu ZHANG Yao | 2008 | Journal of Mechanical Sieienee and Technology2008，12，6： | 1 |
| 11 | Viscous flow field in a mini pump 显示文摘 | LI JINWEI LIU SHUHONG LUO XIANWU | 2007 | Journal of Tsinghua University ( Sci & Tech)2007，47，： | 1 |
| 12 | Survival Outcomes and Prognostic Factors of Surgical Therapy for All Potentially Resectable Intrahepatic Cholangiocarcinoma: a Large Single-Center Cohort Study显示文摘 | Xianwu Luo Lei Yuan Yi Wang Ruiliang Ge Yanfu Sun Gongtian Wei | 2014 | Journal of Gastrointestinal Surgery2014，，3： | 1 |
| 13 | Numerical a- nalysis of cavitation evolution and excited pressure fluc- tuation around a propeller in non-uniform wake 显示文摘 | Ji Bin Luo Xianwu Peng Xiaoxing | 2012 | In- ternational Journal of Muhiphase Flow2012，，43： | 1 |
| 14 | Comparison of CavitationPrediction for a Centrifilgal Pmnp with or without Colu/e Casing 显示文摘 | Xianwu Luo Wei Wei Bin Ji | 2013 | Journal of Mechanical Science and Technology2013，27，6： | 1 |
| 15 | Impeller inlet geometry effect on performance improvement for centrifugal pumps显示文摘 | Xianwu Luo Yao Zhang Junqi Peng Hongyuan Xu Weiping Yu | 2008 | Journal of Mechanical Science and Technology2008，，10： | 1 |
| 16 | Impeller inlet geometry effect on performance improvement for centrifugal pumps显示文摘 | Xianwu Luo Yao Zhang Junqi Peng Hongyuan Xu Weiping Yu | 2008 | Journal of Mechanical Science and Technology2008，，10： | 1 |
| 17 | Cavitation in semi-open centrifugal impellers for a miniature pump显示文摘 | Xianwu Luo Shuhong Liu Yao Zhang Hongyuan Xu | 2008 | Frontiers of Energy and Power Engineering in China2008，，1： | 1 |
| 18 | Cavitation in semi-open centrifugal impellers for a miniature pump显示文摘 | Xianwu Luo Shuhong Liu Yao Zhang Hongyuan Xu | 2008 | Frontiers of Energy and Power Engineering in China2008，，1： | 1 |
| 19 | Impeller inlet geometry effect on performance improvement for centrifugal pumps 显示文摘 | LUO Xianwu ZHANG Yao PENG Junqi | 2008 | Journal of Mechanical Science and Technology2008，22，10： | 1 |
| 20 | Numerical simulation of cavity shedding from a three-dimensional twisted hydrofoil and induced pressure fluctuation by large-eddy simulation 显示文摘 | Luo Xianwu Ji Bin Peng Xiaoxing | 2012 | ASME Journal of Fluids Engineering2012，134，4： | 1 |
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