In order to study the transient flow characteristics of the axial flow pump in the start-up process of the inverted hydraulic turbine, the 6DOF model and the moving grid technology in Fluent software were used to numerically calculate the start-up process of the axial flow pump as a hydraulic turbine based on the flow governing equation and the RNG k-ε turbulence model, and the external characteristics and internal flow field changes were studied. The results show that in the start-up process, the impeller speed first rises sharply, then rises steadily until it reaches a stable speed, the impeller torque first rises sharply and then decreases rapidly for a period of time, and then decreases steadily to a stable value, and the rotation speed is basically the same as the time when the torque reaches the stable value; the vorticity of the impeller basin is mainly distributed at the back of the blade and the outlet of the blade working face, and the maximum vorticity is distributed at the inlet of the back of the blade, and the vorticity distribution position is basically the same as the design condition under the small flow condition, but after the flow field is stable, the maximum vorticity distribution range at the inlet of the back of the blade is obviously larger; when the external load torque is the same, the larger the inlet flow, the shorter the start-up time, the higher the speed after reaching stability.

In order to further investigate the flow characteristics of dry gas seals under complex flow conditions, the influence of turbulence on the steady-state performance of these seals was taken into consideration. The research focused on analyzing the behavior of a classical spiral groove dry gas seal and establishing a governing equation to characterize the pressure distribution in its fluid lubrication's gas film. Numerical simulation was employed to obtain pressure distribution in different flow states within the seal's flow field. By examining structural parameters and operating conditions, their effects on steady-state performance were evaluated using opening force and leakage rate as key metrics. The results indicate significant fluctuations in film pressure within the spiral groove under turbulent flow, with maximum pressure concentrated at its top section. Moreover, turbulent flow exhibits higher opening force compared to laminar flow. Regarding groove depth, an initial increase leads to an increase in opening force followed by a slowdown effect; however, increasing film thickness gradually decreases opening force. The impact of fluid turbulence is intensified at high parameters resulting in an increased leakage rate. Variations in groove depth and film thickness can easily lead to uneven local pressures exacerbating fluctuations in leakage rate. This research provides a theoretical framework for optimizing the design of dry gas seals for high-performance rotating machinery.

To address the resonance risks induced by natural frequency reduction in large-capacity hydraulic turbine runners, this study investigates the wet modal characteristics of turbine blades and the coupling mechanism with hydraulic excitation through fluid-structure interaction (FSI) analysis. The results indicate that under rated operating conditions, the first-order wet modal frequency demonstrates significant spectral deviation from rotational natural frequency, suggesting low resonance probability. As modal order increases, nonlinear amplification of frequency attenuation emerges due to fluid-added mass effects, with notably distinct reduction patterns observed between air and water media. Hydraulic excitation analysis reveals that low-frequency perturbations governed by guide vane count and rotational frequency harmonics constitute primary excitation sources, exhibiting exponential amplitude decay with ascending orders. High-frequency vortex shedding regimes display broad-band energy concentration characteristics. Spectral comparison demonstrates that the dominant excitation frequency band maintains over 1.5fold safety margin relative to the first six wet modal frequencies, while frequency shift characteristics effectively mitigate resonance risks through natural frequency migration.

Focuses on a water supply system at a pump station in Hunan as the research object. Through the two-equation characteristic line method, a mathematical model of the pump station's transient process is constructed. The complete characteristic curves of the pump, the closing time of the pipeline valve, the maximum pressure envelope, the minimum pressure envelope, and the pressure point after the valve are analyzed using Deep Forest, BP neural network, and polynomial regression models. The analysis yields the following conclusions: A reasonable combination of machine learning models and transient flow models can accurately predict and analyze the maximum and minimum pressure envelopes, and the pressure point after the valve in a pressurized water delivery system, providing reliable support for the digital twin optimization scheduling of the water delivery system. Regarding the regression prediction of the complete characteristic curves of the pump, the accuracy distribution trend is as follows: BP neural network>Deep Forest>polynomial regression method. Since the pump does not generally experience reverse rotation during the transition process, and the water flows forward (in the fourth quadrant, reverse dissipation area x∈(4.71, 6.28)), focusing on the regression results of the first, second, and third quadrants shows that the Deep Forest method performs better in regressing the complete characteristic curves of the pump. In terms of regression prediction for maximum/minimum pressure envelopes and valve pressure, the overall expected trend under the Deep Forest model is better than that of the BP neural network. When pressure oscillations caused by the water hammer effect are large and changes are dramatic, the regression results of the BP neural network may produce certain prediction discrepancies.

Displacement following ratio is a crucial parameter that affects the flow control accuracy and stability of the reverse follower proportional valve. In this paper, the mathematical model of a reverse servo proportional valve is established, and the key structural parameters affecting the displacement following ratio of the reverse servo proportional valve are obtained. The influence of each structural parameter on the displacement following ratio is analyzed by AMESim. The results indicate that increasing the diameter of the pilot valve seat hole, reducing the pre-opening degree and width of the feedback valve port, and increasing ratio of the upper and lower cavity areas of the main spool can decrease the dead zone of the pilot poppet valve. When the diameter of the pilot valve seat hole is 3 mm, the width of the feedback valve port is 2.2 mm, and the spring stiffness is 5 N/mm, the displacement following ratio demonstrates better stability while meeting the design requirements. The results provide a theoretical references for the design of reverse-follower proportional valves.

A study on the noise radiation characteristics of a rotary vane vacuum pump was conducted using sound structure coupling technology. Firstly, through theoretical calculations, the theoretical displacement and gas pressure parameters of the rotary vane pump were obtained as a function of the rotor angle, providing boundary conditions for conducting bidirectional fluid structure coupling simulation. Then, a bidirectional fluid structure coupling simulation was conducted on the flow field during the exhaust process of the rotary vane pump, obtaining the distribution characteristics of relevant parameters in the exhaust space and the deformation and force characteristics of the limit block. Finally, numerical simulation of sound structure coupling between airflow and limit plate was conducted, and the vibration and noise characteristics of the limit plate as well as the aerodynamic noise characteristics during the exhaust process were obtained. This article is of great significance for the study of vibration reduction and noise reduction optimization design of rotary vane pumps, and also provides important references for the flow field and noise analysis of other types of vacuum pumps.

Aiming at the problem that the hydraulic proportional valve in the fully hydraulic drilling rig has dead zone characteristics due to nonlinear factors, which makes it difficult to accurately analyze the dynamic characteristics and results in a large deviation between the actual speed and the expected speed of the rotary system, making it difficult to achieve precise control, a model free adaptive iterative learning based automatic control method is proposed for the fully hydraulic drilling rig used in coal mines. This method establishes a mathematical model for a fully hydraulic drilling rig and fully considers the performance of nonlinear factors such as valve port overlap and Coulomb friction under different working conditions through this model. The dynamic characteristics of hydraulic motors and hydraulic proportional valves are analyzed. Discretize the model free adaptive iterative learning controller. After discretization, the controller can ensure that the hydraulic proportional valve will not fail due to dead zone characteristics under the condition of known hydraulic oil volume and spool displacement. The controller also estimates and compensates for time-varying parameters during the discretization process, further improving the accuracy and stability of the control system. The experimental results show that this method can achieve effective automatic control of the fully hydraulic drilling rig while ensuring that the rotational speed of the rotary system is close to the desired speed.

The matching of a turbo air motor with engine had two important indicators: starting time and air consumption. At present, charts or later actual testing are commonly used for estimation both domestically and internationally, without providing a calculation method for starting time and gas consumption. To address the issue of large errors in calculating the starting time and air consumption of turbo air motors using traditional methods, this study used translational and rotational decouple methodology to build an air path model of the turbo air motor and an engine crankshaft model in system simulation software. By integrating the two models, it was able to quantitatively calculate the starting time and air consumption. Through experimental comparison, the pressure error is less than 8%, the speed error is less than 5%, and the air consumption error is less than 7%, The feasibility of this method was verified through experiments, providing a new approach for solving similar problems in the future.

In this paper, the total path length and whether or not the heavy-duty mobile robot collides are taken as the objective functions, and three kinds of constraint conditions are considered synthetically for the heavy-duty mobile robot controlled by electro-hydraulic drive, a path planning model of heavy-duty mobile robot is established to improve the running efficiency of electro-hydraulic heavy-duty mobile robot.The GWO algorithm (Grey Wolf Optimizer, GWO), GA algorithm (Genetic Algorithm, GA), and ACO algorithm (Ant Colony Optimization, ACO) were used for robot path planning simulation analysis. The innovation lies in overcoming the problems of traditional path planning algorithms such as easily falling into local optima, slow convergence speed, and high search path consumption cost. By optimizing algorithm parameters, enhancing convergence speed, optimizing disease wolf handling mechanism, and improving algorithm stability and robustness, the work efficiency and safety of mobile robots can be greatly improved. The results showed that the GWO algorithm planned a total path length, number of turns, and calculation time of 43.45 m, 7 times, and 0.53 s. All three statistical results were superior to the GA algorithm and ACO algorithm, verifying the effectiveness of the proposed robot path planning method based on the grey wolf algorithm.

To solve the problem that parameters tuning method of hydraulic servo controller, and improve work bandwidth of multidimensional vibration system. By analyzing model feature of 3-stage electro-hydraulic system, a method of control parameters tuning is established base on phase-frequency transfer characteristics of system. Using a 6-DOF hydraulic vibration table, a series of tests is carried out. In the single cylinder test, in spool displacement feedback the frequency of -80°phase lag is widened. Finally, 3-DOF frequency sweep and random vibration tests are carried out. The field measurements show that the method described in the paper is completely available.

Taking a high-speed swash plate axial piston pump as the research object, a mathematical model of cylinder overturning moment under radial and axial forces such as inertia force of plunger shoe assembly, oil pressure of plunger cavity, spring preload force and oil film supporting force of distribution pair was established. The variation trend of overturning moment and additional overturning moment of the same coaxiality error under different deviation angles under rated working conditions is discussed under the premise of considering the uneven distribution of cylinder mass around the cylinder. The results show with the increase of deviation angle, the additional overturning moment curve of the cylinder block around x and y axis caused by the radial force presents a decreasing-increasing-decreasing trend, and the additional overturning moment of cylinder block around x axis is much larger than that of the latter, but the latter has a zero crossing situation. Under different deviation angles, the variation trend of the additional overturning moment curve of the cylinder block around x and y axis is the same due to the axial force, but the proportional relationship between the amplitude of the additional moment curve and the deviation angle is exactly opposite in the curve rising and falling stages.

The binding closing work of the servo supporting the joint bearing mainly relies on manual operation by using the bench drilling machine. This method has high requirements on the ability and experience level of using drilling machine, and when the task is suddenly increased, and the work intensity is larger, there is a hidden danger of assembly quality and safety, and the consistency of products is difficult to ensure. In order to reduce the labor intensity, improve the assembly efficiency, enhance the automation level, and promote the optimization and upgrading of the production mode, a method for bearing binding closing was designed. This method is based on pneumatic transmission and uses pneumatic clamping system to realize automatic flow and loading and unloading of the parts to be closed. First of all, the functional requirements of piping closure are explained, and the structure of the closing equipment is designed, and the corresponding working principle of the structure is expounded. Secondly, the important parts are studied and simulated. Finally, the control system is designed. The process method of assembly with binding closing equipment can transform manual guarantee into automatic equipment guarantee, which is of great significance to improve the efficiency of bearing binding closing, improve the production level of aerospace products and optimize and upgrade the production mode.

A method is proposed for typical faults such as “stick slipping” of the main winch and “soil throwing” too slowly of the power head that occur during the construction process of fully hydraulic rotary drilling rigs. Taking a certain model of rotary drilling rig as the research object, based on the investigation and data testing of on-site faults, causes of the faults are analyzed from the hydraulic principles of the main winch and the power head. The mechanisms of the faults are elaborated in detail, and solutions are provided respectively. The rationality of the solution is verified through experiments. Research results show that increasing the oil leakage channel of the BVD valve and removing the pilot damping of the main valve can effectively eliminate the above faults and improve the working efficiency of the drilling rig.

During the operation of a hydraulic driven air conditioning system, it is affected by external environmental factors such as noise and vibration. The signals collected by sensors have nonlinearity and non stationarity, and traditional signal decomposition methods cannot fully capture all dynamic characteristics of the signals, resulting in some signal energy remaining in residual components and reducing the accuracy of detection results. Therefore, an intelligent detection method for sensor faults in hydraulic driven air conditioning systems is proposed. The adaptive processing method using empirical mode decomposition (CEEMDAN) is used to repeatedly decompose residual signals, reduce noise components in residual components, and complete the decomposition and reconstruction of sensor signals. The projection transformation technique in principal component analysis (PCA) is used to transform the decomposed and reconstructed sensor signals into principal component space and residual subspace, achieving effective extraction of fault information. The LS-SVM regression algorithm is used to transfer fault features to a high-dimensional feature space through nonlinear mapping, and the optimal regression function is constructed for linear regression to achieve accurate detection of fault types. The experimental results show that compared with existing feature extraction methods, the proposed method utilizes the projection transformation technique of PCA to transform the decomposed and reconstructed sensor signals into principal component space and residual subspace, effectively extracting fault information, having good generalization ability, and improving fault detection accuracy.

Fault diagnosis of hydraulic pump is the key to maintain crane performance and prolong equipment life. The fault diagnosis of crane hydraulic pump is studied, fault feature extraction and feature fusion are analyzed. A fault diagnosis model of hydraulic pump based on deep residual network is constructed by using smooth pseudo-Wigner-Ville distribution and deep residual network. The unique feature of this method is the introduction of time-oriented smoothing in feature extraction. In feature fusion, residual blocks and shortcut channels are used for network training. The experimental results show that the fault accuracy of the deep residual network model is as high as 99.86% when there is no noise. When the SNR is 10 dB, the accuracy of the deep residual network model is 99.26%. When the SNR is reduced to 2 dB, the accuracy of the deep residual network model drops to 90.69%, while the Inception V1 model is only 74.62%. In addition, the average recognition time of a single sample of the deep residual network model is only 78.19 ms. It shows that the fault diagnosis model of hydraulic pump based on deep residual network model has better diagnostic performance. The practical application satisfies the fault diagnosis engineering of crane hydraulic system.

For durability test of the load holding check valve, the national standard gives a test method. But the test method can only guarantee the opening of the check valve, combined with the check valve in the actual working conditions of the construction machinery. The check valve durability test method for simulating the whole machine under the actual working conditions is proposed. The method effectively simulates the impact process of the check valve spool from the full opening of the positive oil circuit to the instantaneous reverse high-pressure shutdown, and the reverse impact is effectively realized by using accumulators for reverse loading. The test shows that the method can effectively verify the actual impact of the check valve and improve the accuracy of the durability test.

Large oil storage hydraulic cylinders are widely used. These types of hydraulic cylinders have large specifications, complex structures, multiple assembly processes, and are difficult to assemble. The conventional method of assembling by process has low equipment utilization and occupies a large area. To solve the assembly problem of such large oil storage hydraulic cylinders, a multifunctional integrated assembly device for large oil storage hydraulic cylinders has been developed through exploration, improvement, and experimental verification, which integrates processes such as piston rod assembly, hydraulic cylinder assembly, and guide rod assembly into one set of equipment. Through structural design, equipment manufacturing, and physical verification, this device can meet the assembly requirements of large oil storage hydraulic cylinders and increase assembly efficiency by more than twice.

Aiming at the challenges of time-consuming system construction and complex programming in hydraulic circuit data acquisition, this study developed a DIAdem-based hydraulic data acquisition system. By integrating DIAdem modules, the system achieves real-time monitoring and data acquisition of sensor signals. To overcome the limitation of discontinuous automatic data acquisition in conventional models, VBS scripts were specifically developed, enabling effective data collection and hydraulic system control through script-model coordination. Experimental results demonstrate that the DIAdem-based system exhibits favorable performance in data processing accuracy, real-time responsiveness, and operational reliability. This approach provides an efficient technical solution for monitoring and optimization of hydraulic systems.