20 February 2026, Volume 50 Issue 2

    

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  Study on the Design of Flange-housing Bolted Connections in Axial Piston Pumps for Vibration Characteristics

  LAI Rongshen, LIU Shuai, YE Shaogan, BAO Yue, XIA Xiaosong, LIU Wanshan

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 1-10. https://doi.org/10.11832/j.issn.1000-4858.2026.02.001

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  This study focuses on the bolted connection structure between the pump flange and the housing, and establishes a finite element model of the piston pump. The model is validated through both modal analysis experiments and vibration response experiments. Based on the validated model, the influence of four design parameters—bolt position, installation radius, bolt quantity, and bolt size—on modal frequencies and vibration responses is systematically analyzed. The results indicate that a symmetrical bolt arrangement increases certain modal frequencies by up to 12.7% and reduces vibration velocity by up to 21.5%. The installation radius has a relatively minor effect on vibration characteristics. An increase in bolt size leads to higher modal frequencies, but has limited effectiveness in suppressing vibration. Increasing the number of bolts significantly improves the modal frequencies, with a maximum increase of 10.7%, and reduces vibration velocity by as much as 36.1%. An orthogonal experimental design is used to evaluate the relative significance of each parameter. The analysis confirms that bolt position and bolt quantity have the most substantial impact on the modal characteristics and vibration response of the piston pump. Bolt size has a moderate influence, while installation radius has the least effect.
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  Investigation on Impact and Wear Mechanism of Non-circular Planetary Gear Hydraulic Motors

  ZHOU Rulin, ZHAO Zhiwei, LIU Hao, MIAO Xuezhong, ZHANG Xinyu, YUAN Xiaoming

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 11-19. https://doi.org/10.11832/j.issn.1000-4858.2026.02.002

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  The non-circular planetary gear hydraulic motor has great application potential due to its compact structure and high torque output, but it suffers from severe gear impact, serious wear of the valve plate, and low volumetric efficiency. Based on computational fluid dynamics and dynamic analysis, a three-dimensional flow field model of the motor is established. Through numerical simulation and experimental testing, the impact characteristics, valve plate wear mechanism, and structural optimization are systematically investigated. The results show that appropriately enlarging and reshaping the port geometry can effectively reduce the impact peak of the gears and extend the stable operation period by about 55%. Increasing the through-hole diameter of the planetary gear significantly decreases the local axial force and impulse, reducing end-face wear by up to 66.7%. Prototype tests verifies the accuracy of the simulation results, confirming that the proposed optimization scheme improves valve plate wear resistance and motor volumetric efficiency. This study provides theoretical support and experimental evidence for the structural optimization and engineering application of non-circular planetary gear hydraulic motors.
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  Analysis of the Influence of Structural Parameters of Negative Flow Pumps on Outlet Pressure Pulsation at Different Temperatures

  BAI Yun, LUO Xiaobing, YAO Jing, LI Dongming, LIU Yanyan, CHEN Yao

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 53-63. https://doi.org/10.11832/j.issn.1000-4858.2026.02.006

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  As a key driving component in hydraulic systems, the dynamic performance of negative flow pumps directly influences the steady-state and response characteristics of the system. To improve system performance, it is essential to study the influence of internal structural parameters on the outlet pressure pulsation rate. An AMESim simulation model is established based on the operating principle of a negative flow pump. Model validation shows that the maximum relative errors between simulated and experimental values for the front and rear pump pressures are 9.35% and 9.12%, respectively, both within the 10% acceptable threshold. The influence of the control valve and variable mechanism on the outlet pressure pulsation rate at different temperatures is analyzed. The results indicate that the outlet pressure pulsation rate is negatively correlated with the left-side distance of the servo valve orifice and the orifice diameter. However, the outlet pressure pulsation rate is positively correlated with the power valve spool diameter, spool outer diameter, lug diameter, and slot diameter of the swing arm. The results provide a theoretical basis for optimizing the design of the control valve and variable mechanism in negative flow pumps.
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  Efficiency Simulation and Testing of the Hydraulic System for Small Hydraulic Breaker

  LIU Chengqiang, ZHANG Wanli

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 94-101. https://doi.org/10.11832/j.issn.1000-4858.2026.02.010

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  The hydraulic breaker is a commonly used operating tool, which is installed on main machines such as excavators for crushing and demolition operations. To study the efficiency characteristics of the hydraulic system during the operation of the hydraulic breaker, modeling, simulation, and experimental testing are conducted on the hydraulic system of a small hydraulic breaker. Firstly, the working principle of the small hydraulic breaker is analyzed. Then, a model of the hydraulic breaker's system is established based on Simulink, and simulations are carried out. Through this, the pressure curve of the nitrogen chamber in the hydraulic breaker and the instantaneous efficiency curve of the system are obtained. In addition, experimental tests are performed on the operation of a mini-excavator with a small hydraulic breaker. The pressure signals of the nitrogen chamber of the breaker and the hydraulic system are collected, and the instantaneous efficiency and average efficiency of the breaker are derived. This research provides a reference for the study on the efficiency of hydraulic breaker system.
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  Research on Dynamic Characteristics of Hydraulic Shock Testing Apparatus Based for Long Tubular Components

  ZHU Yongzhen, WU Zhe, XU Wenbin, ZHANG Feiran, YANG Gang, LI Baoren

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 102-109. https://doi.org/10.11832/j.issn.1000-4858.2026.02.011

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  Aimed at the scientific challenges in laboratory shock testing for deep sea vessel heavy long tubular components, a fully hydraulical shock testing apparatus based on hydropneumatic spring is developed. Firstly, fundamental principals and dynamic models of the shock response are established. The stored energy during the thermodynamic adiabatic process of the accumulator is expressed using the pressure ratio, and theoretical formulas for the natural frequency and acceleration are derived. Secondly, a simulation analysis is conducted on the feasibility of the shock testing principle with AMESim, revealing the influence laws of loading pressure, oil unloading pipeline diameter and accumulator precharge pressure on the stored energy and peak acceleration. The results show that peak acceleration increases with both higher loading pressure and larger oil unloading pipeline diameter; at three loading pressures of 5, 10 and 15 MPa, the variation trends of the stored energy and the peak acceleration with the precharge pressure exhibit the characteristics of increasing, increasing first and then decreasing and decreasing respectively.
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  Optimization Design of Flow Uniformity in Fractal Channels Based on Physical Decoupling

  TANG Tengfei, LI Yuhang, PENG Yili, ZHANG Dijia

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 20-26. https://doi.org/10.11832/j.issn.1000-4858.2026.02.003

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  Flow uniformity among multiple branches in fractal channel networks is a critical factor determining the performance of hydraulic, pneumatic and heat exchange equipment. Traditional global optimization algorithms often face high computational costs and convergence difficulties due to the significant increase in the dimensionality of the design space. A flow uniformity design strategy based on physical decoupling is proposed. To address these challenges, we propose a flow equalization design strategy based on physical decoupling. Firstly, an iterative geometric correction method is introduced. It utilizes a network topology back-propagation mechanism to map terminal flow deviations into dimensional corrections for each channel level. Secondly, a “layer-wise zero-mean” strategy is applied to decouple the “common-mode” effect from the “differential-mode” effect. This approach ensures precise resistance matching across parallel branches. The strategy is validated using a three-level fractal channel with 20 independent design parameters. The results show that the outlet flow non-uniformity coefficient decreases from 0.1226 to 0.0217 within only 27 CFD iterations. The optimized structure converges to a distinct configuration characterized by widened outer channels and compressed central channels. This study provides a valuable design reference for parameter matching and precision flow control in hydraulic channel networks.
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  Energy-consumption Modeling and Analysis of Conveyor Pushing and Support Moving in Hydraulic Supports Following Shearer Process

  LU Qi, ZHANG Xunan, HE Longlong, PEI Zhenjia, ZHANG Xuhui, CAO Xian'gang

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 27-42. https://doi.org/10.11832/j.issn.1000-4858.2026.02.004

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  Coal mining is a high-energy industry. Intelligent mining pursues both efficiency and low-carbon operation. The conveyor pushing and support moving process of hydraulic supports is the main energy-consumption stage in following shearer process. It represents a key issue for energy optimization. To address this issue, a mathematical energy-consumption model for hydraulic supports following shearer process is established. It uses response surface and correlation analyses to examine the effects of shearer traction speed, pushing-jack inlet pressure, flow rates of leg raising and lowering, and inlet-return pressure. It also analyzes single-factor effects and parameter interactions. A case study on the ZY21000/38/82D hydraulic support in a Shaanxi coal mine shows that traction speed is the dominant factor and has a nonlinear negative relation with both conveyor pushing and support moving energy-consumption. The pushing-jack inlet pressure, leg inlet pressure, and leg raising and lowering flow rates each show linear positive relations with conveyor pushing energy-consumption. The leg return pressure shows a linear negative relation with conveyor pushing energy consumption. Parameter interactions have a significant influence on total energy-consumption. This energy-consumption model provides a theoretical foundation for optimizing hydraulic support parameter configurations. It helps reduce following shearer consumption and promotes green low-carbon transformation in the coal mining industry.
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  Modeling Method and Simulation Verification of Subsea Hydraulic Stepping Actuator

  HOU Guangxin, WU Lu, LU Jing, GE Fei, WANG Songfeng, FENG Miaotao

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 43-52. https://doi.org/10.11832/j.issn.1000-4858.2026.02.005

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  A subsea hydraulic stepping actuator is the core equipment for flow control in deep-sea Christmas trees, and its dynamic performance directly influences the safe and stable operation of subsea production systems. To address the difficulty in accurately characterizing the subsea hydraulic stepping actuator's nonlinear dynamic response in deep-sea high-pressure and low-temperature environment, a high-precision modeling method based on the design and analysis software of subsea-control system is proposed. Using a component-based modeling concept, a simulation model of this actuator is established. It integrates the Stribeck friction model, deep-sea pressure compensation mechanism and hydraulic-mechanical coupling characteristics. Innovatively, the Gevrey function is adopted to smooth the mechanical friction link. It effectively optimizes the numerical stability and response speed of the solver. Through the parameter sensitivity analysis, typical working condition simulation and demonstration project application verification, it is verified that during the opening process of the production choke valve, the deviations of key indicators such as actuator piston displacement and oil supply pressure are all less than 2%, and the nonlinear dynamic response of the actuator can be accurately reproduced. This modeling method provides a reliable technical means for the design optimization and performance prediction of subsea hydraulic stepping actuators, and also lays a modeling technical foundation for achieving independent and controllable development of deep-sea equipment.
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  Hierarchical Adaptive Neuro Fuzzy Inference System Compensated Control for Heavy-load Automatic Guided Vehicle Active Hydro-pneumatic Suspension

  LI Xia, GAO Ya'nan, GAO Lin, HE Tao, LIU Benxue

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 64-73. https://doi.org/10.11832/j.issn.1000-4858.2026.02.007

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  A hierarchical control strategy with adaptive neuro fuzzy inference system compensation is proposed for heavy-duty automatic guided vehicle on unstructured roads. It improves posture control performance under severe nonlinear conditions. The strategy addresses hydro-pneumatic suspension nonlinearity and electromagnetic valve force inaccuracies. The upper layer uses linear quadratic regulator for optimal vertical body control. A fuzzy PID controller suppresses roll motion. Desired active suspension forces are generated. The lower layer applies adaptive neuro fuzzy inference system for force tracking error compensation. It maps force errors to electromagnetic valve control signals. High-precision force tracking is achieved. Simulation results validate the proposed strategy. Under class C road excitation, root mean square vertical and roll accelerations decrease by 30.4% and 38.9%. Under single-side step excitation, peak roll angle decreases by 44%. The strategy shows strong robustness under complex conditions.
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  Research and Verification of Variable Displacement PDU Load Adaptive Control Technology of Wide-body Aircraft

  TIAN Liang, SUN Junshuai, YANG Zhidan, FU Ruxin

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 74-83. https://doi.org/10.11832/j.issn.1000-4858.2026.02.008

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  Variable displacement hydraulic motors can achieve adaptive flow control based on load changes, featuring high efficiency, fast response and low power consumption. However, they also face key technical issues such as a large starting dead zone, low-speed oscillation and significant high pressure internal leakage. To improve the control accuracy and robustness of the variable displacement PDU, we propose a control law design method that combines PID control with feedforward anti-interference. By Simulink modeling simulation and test verification, the proposed control law algorithm can significantly improve dynamic speed response characteristics of the PDU. The test results demonstrate that under the hydraulic condition of 35 MPa and the aerodynamic load of 240 N·m, the flow consumed by the variable displacement PDU is 60.1% lower than that of the same fixed displacement PDU, while the driving efficiency is increased by 100.8% and the total power consumption is reduced by 17.34 kW.
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  Modeling Method of Electro-hydraulic Actuators Based on Physics-informed Neural Networks

  LIN Ziyan, LI Xiaoming

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 84-93. https://doi.org/10.11832/j.issn.1000-4858.2026.02.009

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  Modeling electro-hydraulic actuators is challenging due to their strong nonlinearities and unobservable internal states. To address issues such as low modeling accuracy and poor generalization, we propose an improved physics-informed neural network modeling method. First, a one-dimensional convolutional neural network module is employed to extract temporal features from sensor data. Subsequently, the force balance equation derived from electro-hydraulic actuator dynamics is embedded into the loss function as a physical constraint. This mechanism compensates for the poor interpretability of pure data-driven models and accelerates convergence. Furthermore, to mitigate the interference of sensor noise on physical constraint calculations, a signal smoothing strategy based on local linear fitting is designed. The multi-condition experiments demonstrate that this method effectively balances data fitting with physical consistency. Compared with traditional models, the proposed approach significantly improves prediction accuracy and robustness under limited data conditions.
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  Neural Network Adaptive Kalman Filter Algorithm for Multi-flowmeter Fusion

  ZHOU Yankun, QIAO Zhiwei, YAN Hao

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 110-117. https://doi.org/10.11832/j.issn.1000-4858.2026.02.012

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  RP-3 aviation kerosene is commonly used as the working medium in aero-engine experiments, with both gear and mass flowmeters employed for flow measurement. Different flowmeters exhibit varying accuracy across flow ranges. To address this, a neural network-based adaptive Kalman filter is proposed, in which a neural network dynamically adjusts the measurement noise covariance to improve data fusion. The training dataset is constructed by fitting the relationship between flowmeter frequency and standard flow rate and by calculating measurement variance across different flow ranges using a sliding window. The experiments over the full flow range of 0~120 L/h show that neural network adaptive Kalman filter outperforms the traditional Kalman filter in flow estimation accuracy. The neural network-based adaptive Kalman filter flow measurement platform achieves accuracy within 0.265% of full scale, effectively enhancing the precision and reliability of flow measurements.
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  Modeling and Fault Impact Analysis of Hydraulic Servo System for High-pressure Control Valve in Steam Turbine

  HE Wenbo, FENG Dehu, HUANG Xiangjun, MA Lei, WANG Xingjian

  CHINESE HYDRAULICS & PNEUMATICS. 2026, 50(2): 118-129. https://doi.org/10.11832/j.issn.1000-4858.2026.02.013

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  We analyze the hydraulic servo system of a steam turbine's high-pressure control valve and focuse on fault mechanisms and the influence of major failures. The goal is to develop a simulation model that closely matches actual test bench data. We first investigate the working principles of the electro-hydraulic servo valve and the overall hydraulic servo system. A mathematical model is established and then implemented in the AMESim simulation environment. Model parameters are configured using real measurement data to study how key parameters affect control performance. We inject faults into the model to analyze typical failure mechanisms. This process establishes how major faults impact the servo valve and the overall system performance. For experimental validation, the simulation results are compared with experimental data. The results show a strong consistency between the AMESim model and the experimental data. The error between the steam turbine hydraulic servo system model and the actual test bench data is less than 10%, confirming model accuracy. It provides a valuable reference for advancing the localization of steam turbine hydraulic servo systems.