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Rock fracture mechanism of buffer blasting with cushion layer at the borehole bottom

International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 325-334页

作者： Xinguang Zhu Chenxi Ding Zhe Sui Hong Su Xu Guo School of Civil and Resources engineering University of Science and Technology BeijingBeijing 100083China Key laboratory for Mechanics in fluid Solid Coupling systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Mechanics and Civil engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Chemical and Blasting engineering Anhui University of Science and TechnologyHuainan 232001China

This study primarily investigates the rock fracture mechanism of bottom cushion layer blasting and explores the effects of the bottom cushion layer on rock *** involves analyses of the evolution patterns of blasting stress,characteristics of crack distribution,and rock fracture features in the ***,blasting model experiments were carried out using the dynamic caustics principle to investigate the influence of bottom cushion layers and initiation methods on the integrity of the bottom rock *** experimental results indicate that the combined use of bottom cushion layers and inverse initiation effectively protects the integrity of the bottom rock ***,the process of stress wave propagation and dynamic crack propagation in rocks was simulated using the continuum-discontinuum element method(CDEM)and the Landau explosion source model,with varying thicknesses of bottom cushion *** numerical simulation results indicate that with increasing cushion thickness,the absorption of energy generated by the explosion becomes more pronounced,resulting in fewer cracks in the bottom rock *** illustrates the positive role of the cushion layer in protecting the integrity of the bottom rock mass.

关键词： bottom cushion layer blasting crack propagation continuum-discontinuum element method dynamic stress intensity factor

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Very Large Eddy Simulation of Cavitation from Inception to Sheet/Cloud Regimes by A Multiscale Model

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China Ocean engineering 2021年第3期35卷 361-371页

作者： LI Lin-min WANG Zheng-dong LI Xiao-jun WANG Yan-ping ZHU Zu-chao national-provincial joint engineering laboratory for fluid transmission system technology Zhejiang Sci-Tech UniversityHangzhou 310018China

The cavitating flow in different regimes has the intricate flow structure with multiple time and space *** present work develops a multiscale model by coupling the volume of fluid(VOF)method and a discrete bubble model(DBM),to simulate the cavitating flow in a convergent-divergent test *** Schnerr-Sauer cavitation model is used to calculate the mass transfer rate to obtain the macroscale phase structure,and the simplified Rayleigh-Plesset equation is applied to simulate the growing and collapsing of discrete *** algorithm for bridging between the macroscale cavities and microscale bubbles is also developed to achieve the multiscale *** the flow field,the very large eddy simulation(VLES)approach is *** from inception to sheet/cloud cavitation regimes are taken into account and simulations are *** with the experimental observations,it is shown that the cavitation inception,bubble clouds formation and glass cavity generation are all well represented,indicating that the proposed VOF-DBM model is a promising approach to accurately and comprehensively reveal the multiscale phase field induced by cavitation.

关键词： cavitating flow multiscale model volume of fluid discrete bubble model VLES

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Numerical study of gas-solid two-phase flow and erosion in a cavity with a slope

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Particuology 2022年第3期20卷 25-35页

作者： Zhe Lin Xiwang Sun Yi Li Zuchao Zhu Key laboratory of fluid transmission technology of Zhejiang Province Zhejiang Sci-Tech UniversityHangzhou 310018China national provincial joint engineering laboratory for fluid transmission system technology Zhejiang Sci-Tech UniversityHangzhou 310018China

Gate valve is mainly used to turn on or turn off the pipeline in pneumatic *** the gate valve is fully open,the particles are easy to collide with the cavity rear wall and enter into the cavity,resulting in particles’accumulation in the *** particles in cavity will accumulate between the cavity bottom and the flashboard bottom wall and prevent the gate from turning off ***,the particles’collision with cavity rear wall will cause serious *** the particles’accumulation and erosion will cause the poor sealing of the gate valve,further resulting in the leakage of the pipeline *** reduce the particles’accumulation in cavity and erosion on cavity when the gate valve is fully open,we simplify the gate valve into a cavity structure and study *** find that adding a slope upstream the cavity can effectively reduce the particles’accumulation in the cavity and the erosion on the cavity rear *** this work,Eulerian-Lagrangian method in commercial code(FLUENT)was used to study the gas-solid two-phase flow and erosion characteristics of a cavity with a *** particle distribution shows that the particles with Stokes number St=1.3 and St=13 cannot enter the cavity due to the slope,but the particles with St=0.13 enter the cavity following the *** St=13,the particles collide with the wall many times in the ideal *** results show that the slope can transfer the erosion on cavity rear wall to the slope and reduce the maximum erosion rate of the wall near the cavity to some degrees.

关键词： Cavity with a slope Gas-solid flow Solid particle erosion Stokes number

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Nonlinear Mathematical Modeling and Sensitivity Analysis of Hydraulic Drive Unit

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Chinese Journal of Mechanical engineering 2015年第5期28卷 999-1011页

作者： KONG Xiangdong YU Bin QUAN Lingxiao BA Kaixian WU Liujie national engineering Research Center for Local joint of Advanced Manufacturing technology and Equipment Yanshan University Hebei provincial Key laboratory of Heavy Machinery fluid Power transmission and Control Yanshan University School of Mechanical engineering Yanshan University

The previous sensitivity analysis researches are not accurate enough and also have the limited reference value, because those mathematical models are relatively simple and the change of the load and the initial displacement changes of the piston are ignored, even experiment verification is not conducted. Therefore, in view of deficiencies above, a nonlinear mathematical model is established in this paper, including dynamic characteristics of servo valve, nonlinear characteristics of pressure-flow, initial displacement of servo cylinder piston and friction nonlinearity. The transfer function block diagram is built for the hydraulic drive unit closed loop position control, as well as the state equations. Through deriving the time-varying coefficient items matrix and time-varying free items matrix of sensitivity equations respectively, the expression of sensitivity equations based on the nonlinear mathematical model are obtained. According to structure parameters of hydraulic drive unit, working parameters, fluid transmission characteristics and measured friction-velocity curves, the simulation analysis of hydraulic drive unit is completed on the MATLAB/Simulink simulation platform with the displacement step 2 mm, 5 mm and 10 mm, respectively. The simulation results indicate that the developed nonlinear mathematical model is sufficient by comparing the characteristic curves of experimental step response and simulation step response under different constant load. Then, the sensitivity function time-history curves of seventeen parameters are obtained, basing on each state vector time-history curve of step response characteristic. The maximum value of displacement variation percentage and the sum of displacement variation absolute values in the sampling time are both taken as sensitivity indexes. The sensitivity indexes values above are calculated and shown visually in histograms under different working conditions, and change rules are analyzed. Then the sensitivity index

关键词： nonlinear mathematical model hydraulic drive unit valve-controlled symmetrical cylinder sensitivity analysis sensitivity index

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Effects of rotational speeds on the performance of a centrifugal pump with a variable-pitch inducer

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Journal of Hydrodynamics 2017年第5期29卷 854-862页

作者：郭晓梅朱祖超施高萍黄勇 School of Mechanical and Automotive engineering Zhejiang University of Water Resources and Electric Power The Zhejiang provincial Key laboratory of fluid transmission technology Zhejiang Science and Technology University

The centrifugal pumps usually work at various rotational speeds. The variation in the rotational speeds will affect the internal flow, the external performance, and the anti-cavitation performance of the pump. In order to improve the anti-cavitation performance of the centrifugal pumps, variable-pitch inducers are placed upstream of the impeller. Because the rotational speeds directly affect the flow and the performance of the pump, it is essential to characterize the performance of the pump with a variable-pitch inducer at various rotational speeds. In this paper, the simulations and the experimental tests of a centrifugal pump with a variable-pitch inducer are designed and carried out under various rotational speed conditions. Navier-Stokes equations, coupled with a Reynolds average simulation approach, are used in the simulations. In the experimental tests, the external and anti-cavitation performances of the pump are investigated in a closed system. The following results are obtained from the simulations. Firstly, the velocity in the passage of the inducer rises with the increase of the rotational speed. Secondly, the static pressure escalates on the inducer and the impeller with the increase of the rotational speed. Thirdly, the static pressure distribution on the inducer and the impeller is asymmetric. Fourthly, the anti-cavitation performance of the pump deteriorates with the increase of the rotational speed. Additional results are gathered from an analysis of the experiments. H-Q curves are similar parabolas at various rotational speeds, while η-Q curves are similar parabolas only when n ≤6 000 r/min. The anti-cavitation performance of the pump deteriorates with the increase of the rotational speed. Finally, the simulation results are found to be consistent with the experimental results.

关键词： Centrifugal pumps external characteristics experiments rotational speeds anti-cavitation performance

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Anti-cavitation performance of a splitter-bladed inducer under different flow rates and different inlet pressures

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Science China(Technological Sciences) 2015年第12期58卷 2131-2138页

作者： GUO XiaoMei ZHU ZuChao CUI BaoLing HUANG Yong School of Mechanical and Automotive engineering Zhejiang University of Water Resources and Electric Power Zhejiang provincial Key laboratory of fluid transmission technology Zhejiang Science and Technology University

The anti-cavitation performance of a high-speed centrifugal pump with a splitter-bladed inducer is investigated under different flow rates and different inlet pressures. Simulations and external characteristics experiments are carried out. Static pressure and the vapor volume fraction distributions on the inducer and the impeller of the pump under various operation conditions are obtained. The results show that the cavitation developments on the impeller and on the inducer with the flow rates are reverse, while the development of the inlet pressure on the inducer and the impeller is the same. Cavitation on the impeller increases with the increase of flow rates, and it extends to the near passages with rotating, while cavitation on the inducer is more complex than that on the impeller. Cavitation at the inlet of the inducer decreases with the increase of flow rates, while cavitation at the outlet of the inducer is opposite. The results also show that cavitation development on the impeller and on the inducer with the inlet pressure is the same. Cavitation both decreases with the increase of the inlet pressure at the same flow rate. Furthermore, asymmetric cavitation on the impeller and on the inducer is both observed. And the asymmetric degree of cavitation on the impeller is higher than that on the inducer.

关键词： centrifugal pump anti-cavitation characteristics splitter-bladed inducer two phases flow

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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

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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

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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)

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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

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