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Flow Instability of a Centrifugal Pump Determined Using the Energy Gradient Method

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Journal of Thermal Science 2015年第1期24卷 44-48页

作者： Li Yi Dong Wenlong He Zhaohui Huang Yuanmin Jiang Xiaojun Zhejiang provincial Key laboratory of fluid transmission technology Zhejiang Sci-Tech University Zhejiang Institute of Mechanical & Electrical engineering Co. LTD

The stability of the centrifugal pump has not been well revealed because of the complexity of internal flow. To analyze the flow characteristics of a centrifugal pump operating at low capacity, methods of numerical simulation and experimental research were adopted in this paper. Characteristics of the inner flow were obtained. Standard k-s turbulence models were used to calculate the inner flow of the pump under off-design conditions. The distri- bution of the energy gradient function K was obtained by three-dimensional numerical simulation at different flow rates. The relative velocity component was acquired from the absolute velocity obtained in particle image velocimetry. By comparing with experimental results, it was found that flow instability occurs at the position of maximum K. The flow stability reduces with an increasing flow rate. The research results provide a theoretical basis for the optimization design of a centrifugal pump.

关键词： centrifugal pump flow instability three-dimensional particle image velocimetry numerical simula-tion energy gradient

Effect of Cone Angle on the Hydraulic Characteristics of Globe Control Valve

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Chinese Journal of Mechanical engineering 2015年第3期28卷 641-648页

作者： LIN Zhe WANG Huijie SHANG Zhaohui CUI Baoling ZHU Chongxi ZHU Zuchao Zhejiang provincial Key laboratory of fluid transmission technology Zhejiang Sci-Tech University Zhejiang Windey Co. Ltd.

Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature regarding the influence of valve plug on the internal and external features in globe control valves. Thus the effect of valve plug is studied by CFD and experiment in this paper. It is obtained from external features that the pressure drop between upstream and downstream pressure-sampling position increases exponentially with flow rate. And for small valve opening, the increment of pressure drop decreases with the increase of cone angle（β）. However, with the increase of valve opening, the effect of cone angle diminishes significantly. It is also found that the cone angle has little effect on flow coefficient（Cv） when the valve opening is larger than 70%. But for the cases less than 70%, Cv curve varies from an arc to a straight line. The variation of valve performance is caused by the change of internal flow. The results of internal flow show that cone angle has negligible effect on flow properties for the cases of valve opening larger than 70%. However, when valve opening is smaller than 70%, the pressure drop of orifice decreases with the increase of β, making the reduction in value and scope of the high speed zone around the conical surface of valve plug, and then results in a decreasing intensity of adjacent downstream vortex. Meanwhile, it is concluded from the results that the increase of cone angle will be beneficial for the anti-cavitation and anti-erosion of globe control valve. This paper focuses on the internal and external features of globe control valve that caused by the variation of cone angle, arriving at some results beneficial for the design and usage of globe control valve.

关键词： globe control valve cone angle numerical simulation experiment internal and external features

Planning of a Single Flow Channel in Valve Blocks Based on Additive Manufacturing and the Ant Colony Algorithm

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Chinese Journal of Mechanical engineering 2024年第5期37卷 191-202页

作者： Jin Zhang Ziyang Li Yuying Zhang Yandong Liu Ying Li Xiangdong Kong School of Mechanical engineering Yanshan UniversityQinhuangdao 066004China Hebei provincial Key laboratory of Heavy Machinery fluid Power transmission and Control Qinhuangdao 066004China national&Local joint engineering Research Center for Advanced Manufacturing technology and Equipment Qinhuangdao 066004China State Key laboratory of fluid Power and Mechatronic systems Hangzhou 310027China

As electro-hydrostatic actuator(EHA)technology advances towards lightweight and integration,the demand for enhanced internal flow pathways in hydraulic valve blocks ***,owing to the constraints imposed by traditional manufacturing processes,conventional hydraulic integrated valve blocks fail to satisfy the demands of a more compact channel layout and lower energy ***,the subjectivity in the arrangement of internal passages results in a time-consuming and labor-intensive *** study employed additive manufacturing technology and the ant colony algorithm and B-spline curves for the meticulous design of internal passages within an aviation EHA valve *** layout environment for the valve block passages was established,and path optimization was achieved using the ant colony algorithm,complemented by smoothing using B-spline ***-dimensional modeling was performed using SolidWorks software,revealing a 10.03%reduction in volume for the optimized passages compared with the original *** fluid dynamics(CFD)simulations were performed using Fluent software,demonstrating that the algorithmically optimized passages effectively prevented the occurrence of vortices at right-angled locations,exhibited superior flow characteristics,and concurrently reduced pressure losses by 34.09%-36.36%.The small discrepancy between the experimental and simulation results validated the efficacy of the ant colony algorithm and B-spline curves in optimizing the passage design,offering a viable solution for channel design in additive manufacturing.

关键词： Hydraulic valve block Flow channel B-spline curve Additive manufacturing Ant colony algorithm

Force Compensation Control for Electro-Hydraulic Servo system with Pump-Valve Compound Drive via QFT-DTOC

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Chinese Journal of Mechanical engineering 2024年第2期37卷 228-246页

作者： Kaixian Ba Yuan Wang Xiaolong He Chunyu Wang Bin Yu Yaliang Liu Xiangdong Kong Hebei provincial Key laboratory of Heavy Machinery fluid Power transmission and Control Qinhuangdao 066004China School of Mechanical engineering Yanshan UniversityQinhuangdao 066004China national engineering Research Center for Local joint of Advanced Manufacturing technology and Equipment Yanshan UniversityQinhuangdao 066004China

Each joint of a hydraulic-driven legged robot adopts a highly integrated hydraulic drive unit(HDU),which features a high power-weight ***,most HDUs are throttling-valve-controlled cylinder systems,which exhibit high energy *** contrast,pump control systems offer a high ***,their response ability is *** fully utilize the advantages of pump and valve control systems,in this study,a new type of pump-valve compound drive system(PCDS)is designed,which can not only effectively reduce the energy loss,but can also ensure the response speed and response accuracy of the HDUs in robot joints to satisfy the performance requirements of ***,considering the force control requirements of energy conservation,high precision,and fast response of the robot joint HDU,a nonlinear mathematical model of the PCDS force control system is first *** addition,pressure-flow nonlinearity,friction nonlinearity,load complexity and variability,and other factors affecting the system are considered,and a novel force control method based on quantitative feedback theory(QFT)and a disturbance torque observer(DTO)is designed,which is denoted as QFT-DTOC *** method improves the control accuracy and robustness of the force control system,reduces the effect of the disturbance torque on the control performance of the servo motor,and improves the overall force control performance of the ***,experimental verification is performed using the PCDS performance test *** experimental results and quantitative data show that the QFT-DTOC proposed herein can significantly improve the force control performance of the *** relevant force control method can be used as a bottom-control method for the hydraulic servo system to provide a foundation for implementing the top-level trajectory planning of the robot.

关键词： Legged robot Pump-valve compound drive system(PCDS) Force compensation control Quantitative feedback theory(QFT) Disturbance torque observer(DTO)

Parameters Matching and Control Method of Hydraulic Hybrid Vehicles with Secondary Regulation technology

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Chinese Journal of Mechanical engineering 2009年第1期22卷 57-63页

作者： SUN Hui JIANG Jihai WANG Xin Institute of fluid Power transmission and Control Harbin Institute of technology Harbin 150001 China national Key laboratory of Vehicular transmission Beijing 100072 China

Hydraulic hybrid vehicles （HHV） with secondary regulation technology has the potential of improving fuel economy by operating the engine in the optimum efficiency range and making use of regenerative braking. Hydrostatic transmission technology has the advantage of higher power density and the ability to accept the high rates and high frequencies of charging and discharging, both of which are not favorable for batteries, but the lower energy density requires special power matching design and control strategy to coordinate all the powertrain components in an optimal manner. A multi-objective optimization method is proposed to distinguish the components size values of HHV by considering the requirements of driving cycles and technology aspects. The regenerative braking strategy and energy control strategy based on the optimized HHV is proposed to recovery the braking energy and distribute the regenerated braking energy. Simulation results show that by taking the optimized configuration of HHV, adopting the regenerative braking strategy and energy control strategy are helpful to improve the system efficiency and fuel economy of HHV under urban driving cycles.

关键词： hydraulic hybrid vehicles hydrostatic transmission multi-objective optimization regenerative braking

Research on two-dimensional fluid vibration axial transmission path model of axial piston pump

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High technology Letters 2019年第1期25卷 48-56页

作者： Quan Lingxiao Bai Ruxia Zhang Qiwei Liu Song Lu Yueliang College of Mechanical engineering Yanshan University Hebei provincial Key laboratory of Heavy Machinery fluid Power transmission and Control Nanjing engineering Institute of Aircraft system Jincheng AVIC

High speed and high pressure can enhance the vibration of axial piston pump. A fluid vibration transmission law of axial piston pump is studied in this paper. According to harmonic response analysis results, a transmission path analysis is used to establish a two-dimensional fluid vibration transmission path model in the vertical plane, which has characteristics of multi excitation sources, multi-path and multi-receptors. Model parameters are obtained by experimental and numerical analysis. Matlab is used to solve the model, and acceleration vibration response of three shells is got. To reduce the effect of mechanical vibration, the surface acceleration of pump is tested under low speed condition. Results show that the model can accurately reveal transmission law of fluid vibration and the accuracy is more than 90%. The research lays a foundation for exploring vibration transmission law and vibration control.

关键词： axial piston pump fluid vibration vibration transmission path vibration response

Effects of Oxygen Concentration on Pulsed Dielectric Barrier Discharge in Helium-Oxygen Mixture at Atmospheric Pressure

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Plasma Science and technology 2016年第8期18卷 837-843页

作者：王晓龙谭震宇潘杰陈歆羡 Province Shandong provincial Key laboratory of UHV transmission technology and Equipment School of Electrical EngineeringShandong University

In this work the effects of O_2 concentration on the pulsed dielectric barrier discharge in helium-oxygen mixture at atmospheric pressure have been numerically researched by using a one-dimensional fluid model in conjunction with the chosen key species and chemical *** reliability of the used model has been examined by comparing the calculated discharge current with the reported experiments. The present work presents the following significant results. The dominative positive and negative particles are He_2~＋ and O_2^-, respectively, the densities of the reactive oxygen species（ROS） get their maxima nearly at the central position of the gap, and the density of the ground state O is highest in the ROS. The increase of O_2 concentration results in increasingly weak discharge and the time lag of the ignition. For O_2 concentrations below 1.1%,the density of O is much higher than other species, the averaged dissipated power density presents an evident increase for small O_2 concentration and then the increase becomes weak. In particular,the total density of the reactive oxygen species reaches its maximums at the O_2 concentration of about 0.5%. This characteristic further convinces the experimental observation that the O_2 concentration of 0.5% is an optimal O_2/He ratio in the inactivation of bacteria and biomolecules when radiated by using the plasmas produced in a helium oxygen mixture.

关键词： pulsed dielectric barrier discharge cold atmospheric pressure plasmas helium-oxygen mixture numerical simulation

Effect of Inlet Guide Vanes on the Performance of Small Axial Flow Fan

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Journal of Thermal Science 2017年第6期26卷 504-513页

作者： LIU Yang LIN Zhe LIN Peifeng JIN Yingzi Toshiaki Setoguchi Heuy Dong Kim Key laboratory of fluid transmission technology of Zhejiang Province Zhejiang Sci-Tech University Department of Mechanical engineering Saga University School of Mechanical engineering Andong National University

Effects of the inlet guide vanes on the static characteristics, aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work. The inlet guide vanes with different outlet angle are designed, which are mounted on the casing and located at the upstream of the impeller of the prototype fan. Both steady and unsteady flow simulations arc performed. The steady flow is simulated by the calculations of Navier-Stokes equa- tions coupled with RNG k-epsilon turbulence model, while the unsteady flow is computed with large eddy simu- lation. According to the theoretical analysis, the inlet guide vanes with outlet angle of 60° are regarded as the op- timal inlet guide vanes. The static characteristic experiment is carried out in a standard test rig and the aerody- namic noise is tested in a semi-anechoic room. Then, performances of the fan with optimal inlet guide vanes are compared with those of the prototype fan. The results show that there is reasonable agreement between the simu- lation results and the experimental data. It is found that the static characteristics of small axial flow fan is im- proved obviously after installing the optimal inlet guide vanes. Meanwhile, the optimal inlet guide vanes have effect on reducing noise at the near field, but have little effect on the noise at the far field.

关键词： small axial flow fan inlet guide vanes static characteristics aerodynamic noise internal flow characteristics

Influence of Tip End-plate on Noise of Small Axial Fan

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Journal of Thermal Science 2017年第1期26卷 30-37页

作者： MAO Hongya WANG Yanping LIN Peifeng JIN Yingzi Toshiaki Setoguchi Heuy Dong Kim Key laboratory of fluid transmission technology of Zhejiang Province Zhejiang Sci-Tech University Department of Mechanical engineering Saga University School of Mechanical engineering Andong National University

In this work, tip end-plate is used to improve the noise performance of small axial fans. Both numerical simulations and experimental methods were adopted to study the fluid flow and noise level of axial fans. Four modified models and the prototype are simulated. Influences of tip end-plate on static characteristics, internal flow field and noise of small axial fans are analyzed. The results show that on basis of the prototype, the model with the tip end-plate of 2 mm width and changed length achieved best noise performance. The overall sound pressure level of the model with the tip end-plate of 2 mm width and changed length is 2.4 dB less than that of the prototype at the monitoring point in specified far field. It is found that the mechanism of noise reduction is due to the decrease of vorticity variation on the surface of blades caused by the tip end-plate. Compared with the prototype, the static pressure of the model with the tip end-plate of 2 mm width and changed length at design flow rate decreases by 2 Pa and the efficiency decreases by 0.8%. It is concluded that the method of adding tip end-plate to impeller blades has a positive influence on reducing noise, but it may diminish the static characteristics of small axial fan to some extent. © 2017, Science Press, Institute of engineering Thermophysics, CAS and Springer-Verlag Berlin Heidelberg.

关键词： Axial flow Fans Flow of fluids Noise abatement Numerical methods