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| 1 | CFD Investigation of the Influence of Volute Geometrical Variations on Hydrodynamic Characteristics of Circulator Pump显示文摘Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on hydrodynamic characteristics of pump and the mechanism. However, the existing studies are limited to investigate the influence of only one or two volute geometrical parameters each time, and a systematic study of the influence of the combinations of different volute geometrical parameters on the pump's hydrodynamic characteristics is missing. In this paper, a study on the understanding of the influence of volute geometrical variations on hydrodynamic characteristics of a high speed circulator pump by using computational fluid dynamics(CFD) technology is presented. Five main volute geometrical parameters D_3, A_8, a_0, j_0 and Rt are selected and 25 different volute configurations are generated by using design of experiments(DOE) method. The 3D unsteady flow numerical simulations, which are based on the SST k-w turbulence model and sliding mesh technique provided by CFX, are executed on the 25 different volute configurations. The hydraulic performance, pressure pulsation and unsteady radial force inside the pump at design condition are obtained and analyzed. It has been found that volute geometrical parameters D_3 and A_8 are major influence factors on hydrodynamic characteristics of the pump, while a_0, j_0 and Rt are minor influence factors. The minimum contribution from both D_3 and A_8 is 58% on head, and maximum contribution from both D_3 and A_8 is 90% on pressure pulsation. Regarding the pressure pulsation intensity, two peaks can be found. One is in the tongue area and the other is in the diffusor area. The contributions are around 60% from tongue and 25% from diffusor, respectively. The amplitude of pressure pulsation has a quadratic polynomial functional relationship with respect to D_3/D_2 and A_8/A_(10), and fluctuating level of radial force has a quadratic polynomial functional relationship with respect to D_3/D_2. While for the other volute parameters a_0, j_0 and Rt, no special function has been found related to pressure pulsation and radial force. The presented work could be a useful guideline in engineering practice when designing a circulator pump with low hydrodynamic force. | WU Denghao YUAN Shouqi REN Yun MU Jiegang YANG Youdong LIU Jian | 2016 | Chinese Journal of Mechanical Engineering2016，29，2： | 11 |
| 2 | Investigation of Self-Priming Process of a Centrifugal Pump with Double Blades显示文摘The gas-liquid two-phase flow patterns of a centrifugal pump during the self-priming process were investigated numerically and experimentally.The Euler-Euler multiphase model and SST k-ω turbulence model were applied for simulating the self-priming process.Meanwhile,the changes of motor speed and self-priming height were considered in the simulation.The overall transient two-phase flow features and water level distributions were mapped.Results showed that the self-priming process was divided into three stages.The liquid level in inlet-pipe rose in oscillation during self-priming process.The variations of water level during self-priming process of numerical simulation and test result agreed well.The inlet-pipe(Ver)was filled at 22 s and 24 s respectively numerically and experimentally.The bubble cloud circulated in the volute during middle stage of self-priming process,and breakup into smaller bubbles by shear force and tongue,and then discharged into chamber.The bubbles in the outlet-pipe mainly included bubbly flow and slug flow at the last stage of self-priming process,which is morphologically consistent with the test results.Also,during the self-priming process,the reflux liquid was pressed by blades and fully mixed with gas;that is the way to realizing the function of self-priming. | QIAN Heng MOU Jiegang REN Yun ZHU Zhibing LIU Nuojia ZHENG Shuihua WU Denghao | 2021 | Journal of Thermal Science2021，30，3： | 3 |
| 3 | Unsteady Flow and Structural Behaviors of Centrifugal Pump under Cavitation Conditions显示文摘Cavitation has a significant e ect on the flow fields and structural behaviors of a centrifugal pump. In this study, the unsteady flow and structural behaviors of a centrifugal pump are investigated numerically under di erent cavitation conditions. A strong two-way coupling fluid-structure interaction simulation is applied to obtain interior views of the e ects of cavitating bubbles on the flow and structural dynamics of a pump. The renormalization-group k-ε turbulence model and the Zwart–Gerbe–Belamri cavitation model are solved for the fluid side, while a transient structural dynamic analysis is employed for the structure side. The di erent cavitation states are mapped in the head-net positive suction head(H-NPSH) curves and flow field features inside the impeller are fully revealed. Results indicate that cavitating bubbles grow and expand rapidly with decreasing NPSH. In addition, the pressure fluctuations, both in the impeller and volute, are quantitatively analyzed and associated with the cavitation states. It is shown that influence of the cavitation on the flow field is critical, specifically in the super-cavitation state. The e ect of cavitation on the unsteady radial force and blade loads is also discussed. The results indicate that the averaged radial force increased from 8.5 N to 54.4 N in the transition progress from an onset cavitation state to a super-cavitation state. Furthermore, the structural behaviors, including blade deformation, stress, and natural frequencies, corresponding to the cavitation states are discussed. A large volume of cavitating bubbles weakens the fluid forces on the blade and decreases the natural frequencies of the rotor system. This study could enhance the understanding of the e ects of cavitation on pump flow and structural behaviors. | Denghao Wu Yun Ren Jiegang Mou Yunqing Gu Lanfang Jiang | 2019 | Chinese Journal of Mechanical Engineering2019，32，1： | 3 |
| 4 | Influence of the Area of the Reflux Hole on the Performance of a Self-Priming Pumnp显示文摘The self-priming process of a pump involves a complex gas-liquid two-phase flow.Studying the distribution of gas and water and the evolution of their flow in the pump is of great importance to optimize this process and shorten the pump self-priming time.In the present study,a standard k-εturbulence model and a multiphase flow model have been used to simulate the self-priming pump process considering four different reflux hole areas.A comparison of the distribution of air and water distribution on the axial surface and inside the volume have been carried out for the different considered cases.The pattern formed by the streamlines at different times during the whole self-priming process has also been investigated.The results show that the velocity at the trailing edge of the impeller outlet is the largest.The flow in the pump cavity is.complicated by the formation of vortices.The number,shape and location of the vortices change depending on the considered configuration. | Jiegang Mou Fengye Zhang Haoshuai Wang Denghao Wu | 2019 | Fluid Dynamics & Materials Processing2019，15，3： | 1 |
| 5 | A Numerical Investigation on the Characteristics of the Radial Force in a Cycloid Gerotor Pump显示文摘In order to improve the performances of a cycloid gerotor pump,the variations of the radial force induced by different rotating speeds and outlet pressures are analyzed numerically.Using the numerical simulations as a basis,an improved oil inlet and outlet groove structure is proposed.The results show that the radial force decreases with the decrease of the outlet pressure and of the rotor speed.Compared with the original model,the large-end oil inlet line and pressure line of the new oil groove are claw-shaped.This configuration can effectively weaken the pressure changes inside the gerotor pump and reduce accordingly the radial force on the inner rotor. | Lingzhi Yu Yunqing Gu Jiegang Mou Denghao Wu Zhenfu Chen Yun Ren | 2020 | Fluid Dynamics & Materials Processing2020，16，5： | 0 |
| 6 | LES Analysis of the Unsteady Flow Characteristics of a Centrifugal Pump Impeller显示文摘Stall phenomena increase the complexity of the internal flow in centrifugal pump impellers.In order to tackle this problem,in the present work,a large eddy simulation(LES)approach is applied to determine the characteristics of these unstable flows.Moreover,a vorticity identification method is used to characterize quantitatively the vortex position inside the impeller and its influencing area.By comparing the outcomes of the numerical simulations and experimental results provided by a Particle Image Velocimetry(PIV)technique,it is shown that an apparent“alternating stall”phenomenon exists inside the impeller when relatively small flow rate conditions are considered.The stall is generated near the suction side of the blade inlet,grows towards the high-pressure side of the blade in the circumferential direction,and gradually attenuates.As the flow rate decreases,the number of stalls remains unchanged,while the related influencing area and strength gradually increase and the circumferential velocity increases. | Ting Zhang Denghao Wu Shijun Qiu Peijian Zhou Yun Ren Jiegang Mou | 2022 | Fluid Dynamics & Materials Processing2022，18，5： | 0 |
| 7 | Control of rice ratooning ability by a nucleoredoxin that inhibits histidine kinase dimerization to attenuate cytokinin signaling in axillary buds显示文摘Rice ratooning,the fast outgrowth of dormant buds on stubble,is an important cropping practice in rice production.However,the low ratooning ability(RA)of most rice varieties restricts the application of this cost-efficient system,and the genetic basis of RA remains unknown.In this study,we dissected the genetic architecture of RA by a genome-wide association study in a natural rice population.Rice ratooning ability 3(RRA3),encoding a hitherto not characterized nucleoredoxin involved in reduction of disulfide bonds,was identified as the causal gene of a major locus controlling RA.Overexpression of RRA3 in rice significantly accelerated leaf senescence and reduced RA,whereas knockout of RRA3 significantly delayed leaf senescence and increased RA and ratoon yield.We demonstrated that RRA3 interacts with Oryza sativa histidine kinase 4(OHK4),a cytokinin receptor,and inhibits the dimerization of OHK4 through disulfide bond reduction.This inhibition ultimately led to decreased cytokinin signaling and reduced RA.In addition,variations in the RRA3 promoter were identified to be associated with RA.Introgression of a superior haplotype with weak expression of RRA3 into the elite rice variety Guichao 2 significantly increased RA and ratoon yield by 23.8%.Collectively,this study not only uncovers an undocumented regulatory mechanism of cytokinin signaling through de-dimerization of a histidine kinase receptor-but also provides an eximious gene with promising value for ratoon rice breeding. | Yilong Yao Denghao Xiang Nai Wu Yao Wang Yu Chen Yang Yuan Ying Ye Dan Hu Chang Zheng Yu Yan Qingya Lv Xiaokai Li Guoxing Chen Honghong Hu Haiyan Xiong Shaobing Peng Lizhong Xiong | 2023 | Molecular Plant2023，16，12： | 0 |
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