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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 | Influence of Tip Clearance on Unsteady Flow in Automobile Engine Pump显示文摘The automobile engine pump is an important part of the automobile cooling system,and has a direct influence on the engine performance.Based on the SST k-ωturbulence model,unsteady numerical simulation for an automobile engine pump with different tip clearances was carried out by Fluent.To study the flow field characteristics and pressure fluctuation,the characteristics of secondary flow distribution in volute are also analyzed.The result shows that the pressure fluctuation characteristics of the flow field show obvious periodic variation at different levels of tip clearances.The peak value of pressure fluctuation at each monitoring point is dependent on the blade frequency.At the same time,with the increase of the tip clearance,the pressure fluctuation in the blade and volute is gradually increased,while the pressure fluctuation at the tip is reduced clearance.The pressure gradient in the pump also varies periodically with the rotation of the impeller.With the increase of the tip clearance,the pressure of the impeller,volute and tip clearance is gradually decreased.There are secondary flow vortexes inside the impeller,volute outlet and volute section.With the increase of tip clearance,the vortex intensity in the impeller channel is weakened,and the vortex strength at the volute outlet is intensified.On the cross section of the volute,the morphology of most vortexes has insignificant changes,but the vortex intensity decreased. | Jiacheng Dai Jiegang Mou Tao Liu | 2020 | Fluid Dynamics & Materials Processing2020，16，2： | 3 |
| 3 | 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 |
| 4 | Relationship between joint development in rock and coal seams in the southeastern margin of the Ordos basin显示文摘To predict joint development characteristics of coal seams, joint characteristics of rock seams from 88field stations were observed and comparisons were made between joint characteristics of coal and rock seams at 10 coal outcrops. Additionally, detailed joint measurements of underground coal seams were taken at two coal mines. This study investigated the effects of seam thickness, lithology, and structure on joint development and established the relationship between joint development of coal and rock seams, which allowed predictions of predominant joint densities for the No.5 coal seam in the southeastern margin of the Ordos basin. The results show that outcrop and underground coal seams exhibit the same joint systems as rock seams. The joints are mainly upright. Predominant joints strike 55° on average, followed by joints striking 320°. The joint density of the coal seam is 18.7–22.5 times that of the sandstone seam at the same thickness. The predominant joint density of the No.5 coal seam, controlled by the structure, is 4–20 joints per meter. Joint densities exhibit high values at intersecting areas of faults and folds and decrease values in structurally stable areas. The permeability increases exponentially with increasing density of the predominant joints. | Wang Linlin Jiang Bo Wang Jilin Qu Zhenghui Li Pei Liu Jiegang | 2014 | International Journal of Mining Science and Technology2014，24，2： | 1 |
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