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Characterization on the hydrodynamics of a covering-plate Rushton impeller

Chinese Journal of Chemical Engineering 2018年第6期26卷 1392-1400页

作者： Tenglong Su Fengling Yang Meiting Li Kanghui Wu School of Mechanical Engineering Shandong University Key Laboratory of High Efficiency and Clean Mechanical Manufacture(Shandong University) Ministry of EducationShandong University

A modified Rushton impeller with two circular covering-plates mounted on the upper and lower sides of the blades was *** are gaps between the plates and the *** turbulent hydrodynamics was analyzed by the computational fluid dynamics(cfd) ***,the reliability of the numerical model and simulation method was verified by comparing with the experimental results from ***,the power consumption,flow pattern,mean velocity and mixing time of the covering-plate Rushton impeller(RT-C) were studied and compared with the standard Rushton impeller(RT) operated under the same *** show that the power consumption can be decreased about 18%.Compared with the almost unchanged flow field in the lower stirred tank,the mean velocity was increased at the upper half of the stirred *** in the impeller region,the mean axial and radial velocities were increased,the mean tangential velocity was *** addition,the average mixing time of RT-C was shortened about 4.14% than the counterpart of *** conclusions obtained here indicated that RT-C has a more effective mixing performance and it can be used as an alternative of RT in the process industries.

关键词： Covering-plate Rushton impeller（RT-C） Power consumption Flow pattern Mean velocity Mixing time computational fluid dynamics（cfd）

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URANS simulations of the tip-leakage cavitating flow with verification and validation procedures

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Journal of Hydrodynamics 2018年第3期30卷 531-534页

作者： Huai-yu Cheng Xin-ping Long Yun-zhi Liang Yun Long Bin Ji State Key Laboratory of Water Resources and Hydropower Engineering Science School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan UniversityWuhan 430072China Science and Technology on Water Jet Propulsion Laboratory Shanghai 200011China

In the present paper, the Vortex Identified Zwart-Gerber-Belamri（VIZGB） cavitation model coupled with the SST-CC turbulence model is used to investigate the unsteady tip-leakage cavitating flow induced by a NACA0009 hydrofoil. A qualitative comparison between the numerical and experimental results is made. In order to quantitatively evaluate the reliability of the numerical data, the verification and validation（V＆V） procedures are used in the present paper. Errors of numerical results are estimated with seven error estimators based on the Richardson extrapolation method. It is shown that though a strict validation cannot be achieved, a reasonable prediction of the gross characteristics of the tip-leakage cavitating flow can be obtained. Based on the numerical results, the influence of the cavitation on the tip-leakage vortex（TLV） is discussed, which indicates that the cavitation accelerates the fusion of the TLV and the tip-separation vortex（TSV）. Moreover, the trajectory of the TLV, when the cavitation occurs, is close to the side wall.

关键词： Cavitation computational fluid dynamics（cfd） tip-leakage vortex（TLV） verification and validation（V＆V）

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A transient bulk flow model with circular whirl motion for rotordynamic coefficients of annular seals

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Chinese Journal of Aeronautics 2018年第5期31卷 1085-1094页

作者： Peng XIA Zhansheng LIU Xiangyu YU Jingming ZHAO School of Energy Science and Engineering Harbin Institute of Technology

Bulk flow model with perturbation simplification has been used to calculate rotordynamic coefficients in annular seals which have significant influences on the dynamic behavior of rotors in turbomachinery. In this work, a transient bulk flow model with arbitrary rotor motion is developed, and the boundary conditions and friction factor in the model are calibrated with steady computational fluid dynamics（cfd） analysis. The numerical solution scheme is developed based on the finite element method to obtain the transient reaction force in the seal clearance. With a periodic circular rotor orbit, the transient forces at multiple whirling frequencies are used to evaluate the rotordynamic coefficients. The leakage flowrate of cfd analysis has good agreement with experimental results and the calibrated parameters in bulk flow model are dependent on operating conditions. Although cfd calibration improves the accuracy of the perturbed bulk flow model, the direct damping is overestimated and the cross-coupled damping is underestimated. Compared with the perturbed model, the predictions of the transient bulk flow model are more agreeable with the experiment.

关键词： Annular seals Bulk flow computational fluid dynamics（cfd） Rotordynamic Turbulence

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cfd Simulation of Local and Global Mixing Time in an Agitated Tank

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Chinese Journal of Mechanical Engineering 2017年第1期30卷 118-126页

作者： LI Liangchao XU Bin Key Laboratory of Testing Technology for Manufacturing Process of Ministry of Education Southwest University of Science and TechnologyMianyang 621010China

The Issue of mixing efficiency in agitated tanks has drawn serious concern in many industrial processes. The turbulence model is very critical to predicting mixing process in agitated tanks. On the basis of computational fluid dynamics（cfd） software package Fluent 6.2, the mixing characteristics in a tank agitated by dual six-blade-Rushton-turbines（6-DT） are predicted using the detached eddy simulation（DES） method. A sliding mesh（SM） approach is adopted to solve the rotation of the impeller. The simulated flow patterns and liquid velocities in the agitated tank are verified by experimental data in the literature. The simulation results indicate that the DES method can obtain more flow details than Reynolds-averaged Navier-Stokes（RANS） model. Local and global mixing time in the agitated tank is predicted by solving a tracer concentration scalar transport equation. The simulated results show that feeding points have great influence on mixing process and mixing time. Mixing efficiency is the highest for the feeding point at location of midway of the two impellers. Two methods are used to determine global mixing time and get close result. Dimensionless global mixing time remains unchanged with increasing of impeller speed. Parallel, merging and diverging flow pattern form in the agitated tank, respectively, by changing the impeller spacing and clearance of lower impeller from the bottom of the tank. The global mixing time is the shortest for the merging flow, followed by diverging flow, and the longest for parallel flow. The research presents helpful references for design, optimization and scale-up of agitated tanks with multi-impeller.

关键词： agitated tank mixing time computational fluid dynamics（cfd） detached eddy simulation（DES） numerical simulation

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Combustion simulation and key parameter optimization for opposite axial piston engine in small-scale

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Journal of Central South University 2015年第9期22卷 3397-3408页

作者：张雷徐海军潘存云徐小军 College of Mechatronics Engineering and Automation National University of Defense Technology

As potential alternative power sources used in portable electric generators, opposite axial piston engines in small-scale were investigated to show their advantages in power density. A novel cylinder charge system was introduced, based on which a quasi-dimension model and a cfd(computational fluid dynamics) model were established. Comparison of those two models was carried out to validate the quasi-dimension model. Furthermore, optimal diameter of charge cylinder and speed were determined after evaluating the quasi-dimension model based on different parameters. High agreement between the quasi-dimension model and the cfd model validates the quasi-dimension model. Further studies show that the power of engine increases with the diameter of charge cylinder. However, a too big charge cylinder lowers the fuel efficiency instead. Taking economic influence into consideration the charge cylinder should be 1.4 times power cylinder, which could ensure the power density, volumetric efficiency and fuel economic at the same time. Axial piston engine running at 1.0×104 r/min could achieve a better overall performance. The maximal power of engine with optimal parameters is 0.82 k W, which fits the power need of the portable electric generators completely.

关键词： opposite axial piston engine quasi-dimension model computational fluid dynamics（cfd） optimal design

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Hydraulic Optimization of a Double-channel Pump's Impeller Based on Multi-objective Genetic Algorithm

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Chinese Journal of Mechanical Engineering 2015年第3期28卷 634-640页

作者： ZHAO Binjuan WANG Yu CHEN Huilong QIU Jing HOU Duohua School of Energy and Power Engineering Jiangsu University Shanghai Kaiquan Pump (Goup) Co. Ltd

computational fluid dynamics（cfd） can give a lot of potentially very useful information for hydraulic optimization design of pumps, however, it cannot directly state what kind of modification should be made to improve such hydrodynamic performance. In this paper, a more convenient and effective approach is proposed by combined using of cfd, multi-objective genetic algorithm（MOGA） and artificial neural networks（ANN） for a double-channel pump＇s impeller, with maximum head and efficiency set as optimization objectives, four key geometrical parameters including inlet diameter, outlet diameter, exit width and midline wrap angle chosen as optimization parameters. Firstly, a multi-fidelity fitness assignment system in which fitness of impellers serving as training and comparison samples for ANN is evaluated by cfd, meanwhile fitness of impellers generated by MOGA is evaluated by ANN, is established and dramatically reduces the computational expense. Then, a modified MOGA optimization process, in which selection is performed independently in two sub-populations according to two optimization objectives, crossover and mutation is performed afterword in the merged population, is developed to ensure the global optimal solution to be found. Finally, Pareto optimal frontier is found after 500 steps of iterations, and two optimal design schemes are chosen according to the design requirements. The preliminary and optimal design schemes are compared, and the comparing results show that hydraulic performances of both pumps 1 and 2 are improved, with the head and efficiency of pump 1 increased by 5.7% and 5.2%, respectively in the design working conditions, meanwhile shaft power decreased in all working conditions, the head and efficiency of pump 2 increased by 11.7% and 5.9%, respectively while shaft power increased by 5.5%. Inner flow field analyses also show that the backflow phenomenon significantly diminishes at the entrance of the optimal impellers 1 and 2, both the area of vort

关键词： double-channel pump＇s impeller multi-objective genetic algorithm artificial neural network computational fluid dynamics（cfd） uni

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cfd simulation of ammonia-based CO_2 absorption in a spray column

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Journal of Southeast University(English Edition) 2015年第4期31卷 479-488页

作者：赵杰金保昇徐寅东南大学能源热转换及其过程测控教育部重点实验室南京210096

A comprehensive computational fluid dynamics（cfd） model is developed based on the gas-liquid two-phase hydrodynamics,gas-liquid mass-transfer theory and chemical reaction kinetics,and the ammonia-based CO2 absorption in a spray column is numerically *** Euler-Lagrange model is applied to describe the behavior of gas-liquid twophase flowand heat *** dual-film theory and related correlations are adopted to model the gas-liquid mass transfer and chemical absorption *** volatilization model of multi-component droplet is utilized to account for ammonia *** effect of operation parameters on CO2 removal efficiency is numerically *** results showa good agreement with the previous experimental data,proving the validity of the proposed *** profile studies of gasphase velocity and CO2 concentration suggest that the flowfield has a significant impact on the CO2 concentration ***,the local CO2 absorption rate is influenced by both local turbulence and the local liquid-gas ***,the velocity field of gas phase is optimized by the method of adjusting the orifice plate,and the results showthat the CO2 removal efficiency is improved by approximately 4%.

关键词： CO_2 absorption spray column computational fluid dynamics（cfd） aqueous ammonia

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Modeling and Analysis of A Rotary Direct Drive Servovalve

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Chinese Journal of Mechanical Engineering 2014年第5期27卷 1064-1074页

作者： YU Jue ZHUANG Jian YU Dehong School of Mechanical Engineering Xi'an Jiaotong University

Direct drive servovalves are mostly restricted to low flow rate and low bandwidth applications due to the considerable flow *** studies mainly focus on enhancing the driving force,which in turn is limited to the development of the magnetic *** at reducing the flow forces,a novel rotary direct drive servovalve（RDDV）is introduced in this *** RDDV servovalve is designed in a rotating structure and its axially symmetric spool rotates within a certain angle range in the valve *** servovalve orifices are formed by the matching between the square wave shaped land on the spool and the rectangular ports on the *** order to study the RDDV servovalve performance,flow rate model and mechanical model are established,wherein flow rates and flow induced torques at different spool rotation angles or spool radiuses are *** model analysis shows that the driving torque can be alleviated due to the proposed valve *** fluid dynamics（cfd）analysis using ANSYS/FLUENT is applied to evaluate and validate the theoretical *** addition,experiments on the flow rate and the mechanical characteristic of the RDDV servovalve are carried *** simulation and experimental results conform to the results of the theoretical model analysis,which proves that this novel and innovative structure for direct drive servovalves can reduce the flow force on the spool and improve valve frequency response *** research proposes a novel rotary direct drive servovalve,which can reduce the flow forces effectively.

关键词： direct drive servovalve computational fluid dynamics（cfd） flow rate flow induced torque

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Numerical simulation of two-phase flow field in underwater sealing device based on dynamic mesh

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Journal of Measurement Science and Instrumentation 2015年第3期6卷 253-257页

作者：张学伟李强吕梦柔中北大学机电工程学院山西太原030051

In order to speed underwater launch of minor-caliber weapons,a sealing device can be set in front of underwater muzzle to separate water,preventing the muzzle from water *** establishing and simplifying the model of underwater weapon sealing device and unstructured mesh computing domain model based on computational fluid dynamics（cfd）,dynamic mesh and user defined function（UDF）,the N-S equation is solved and the numerical analysis and calculation of the complex two-phase flow inside the sealing device are carried *** results show that the gas discharged from the sealing device is conducive to the formation of the projectile *** the projectile is launched at 5munder water,the shock wave before and after the projectile has impact on the box body up to 100 MPa,therefore the sealing device must be strong *** research results have the vital significance to the design of underwater weapon sealing device and the formation of the projectile supercavitation.

关键词： two-phase flow supercavitation sealing device computational fluid dynamics（cfd） dynamic mech

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A computational fluid dynamics Method for Resistance Prediction of the Floating Hull of Wave Glider

A Computational Fluid Dynamics Method for Resistance Predict...

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The 2014 International Conference on Materials Science and Engineering Technology(MSET 2014)

作者： Aladdin Elhadad Duan Wenyang Deng Rui College of Shipbuilding Engineering Harbin Engineering University

ISBN: (纸本)9783038351023

The wave glider is a surface vehicle with an attached sub-surface wing system which propels the surface component forward, negating the need for a motorWave glider could be used for intelligence, surveillance, passive monitoring of marine life, monitoring exclusive economic zones for fishing and other economic resources that are important and useful to coastal countriesMonitoring of coastal waters normally requires large amounts of expensive surveillanceThey can be used to find and research resources and fisheries at a fraction of the cost of other methodsSince the wave glider can either be programmed for a journey or to keep station, it is looked at as an alternative for expensive moored buoysIn this paper we present a method focused on the mesh generation to predict calm water resistance for the floating part of the wave glider（the hull）In this study a wigley hull form（4m） used as the floating hull has been investigated in order to predict the fluid flow of the ship using computational fluid dynamics（cfd）Calculations for total resistance are carried out for Froude numbers in the range of 0.10 to 0.40Commercial cfd software fluent is used to investigate the fluid flow of wigley hullThree different mesh sizes are used in this study to calculate the mesh effectsThe results obtained from cfd calculations for total resistance are compared with the experimental results for accuracy of the solution parametersThe comparison shows a good agreement between experimental and cfd resultsThe method is evaluated by comparing the numerical predictions for wigley hull form（2m） with wigley hull form（4m） using the same mesh sizes under the same conditions in an attempt to design the floating hull of wave gliderThe results obtained from cfd calculations are compared for accuracy of the solution parameters and the method is useful and acceptable.

关键词： Wave glider Wigley hull Resistance computational fluid dynamics（cfd）

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