Particle erosion wear phenomenon occurs on the blade surface when wind turbines operate in sandy and dusty weather, leading to changes in blade morphology and degradation of its aerodynamic performance. In this paper, the dynamic erosion prediction method based on the coupled flow-solid-erosion model is used to simulate the erosion process of the NREL S809 straight wing section, to study the dynamic evolution of the surface wear caused by the particle erosion of the S809 straight wing section, and to analyze the change of the surface morphology of the S809 straight wing section and its impact on the aerodynamic performance under the conditions of different particle sizes. The study shows that: with the advancement of the erosion time, the cumulative effect of the erosion wear on the leading edge of the S809 straight wing segment surface is obvious, and the wear caused by the particles on the surface of the wing segment is intensified, and the depth of the erosion crater is gradually increased, which results in the fluctuation of the pressure coefficient of the surface of the airfoil and the increase of the degree of the static pressure disorder. With the gradual change of leading edge wear morphology, the turning position of the suction surface of the airfoil is gradually disorganized.

Aiming at the high performance design of end face structure for spiral groove mechanical seals with liquid film lubrication, the entropy production loss method was adopted to carry out the numerical calculation of the three-dimensional turbulence flow field and groove optimization design of spiral groove mechanical seal; The pressure distribution of flow fields with different grooves were analyzed; The leakage rate, opening force and entropy production loss of the seal at different speed and groove depth conditions were calculated. The results show that the optimal spiral angle, groove-ridge ratio, groove-dam ratio and groove depth is 20°, 0.42, 0.63 and 13 μm, respectively; the optimal seal end face dynamic pressure opening ability is large, and the flow entropy production loss is small; The leakage rate and opening force increase linearly with the rotational speed and groove depth, the entropy production loss increases parabolically with the rotational speed and vary little with groove depth. The multi-objective optimization design method constructed can provide design guidance for low leakage, and low-energy mechanical seal structures.

For the issue that the current hydraulic design of centrifugal pump can only meet the design condition, a hydraulic design method for centrifugal pumps under three working conditions is proposed. Utilizing the fundamental principle of centrifugal pump, the calculation relationships of impeller outlet geometric parameters regarding the theoretical head, actual head and flow rate of centrifugal pump are derived. The WEZ80×50 centrifugal pump is selected as the research object, with the key outlet geometric parameters of the impeller as the target variables, by establishing a hydraulic loss model, the performance to calculate performance parameters of off-design points and a program is written to verify the design method. A set of optimal centrifugal pump impeller geometric parameter is determined using the threshold iteration method. The accuracy of the design method is verified through numerical simulation and experimental methods. The results show that the performance of the centrifugally redesigned pump impeller at three working points can meet the design requirements, and the errors in head and hydraulic efficiency are within 5%, indicating that the design method proposed in this article can meet the design requirements of centrifugal pumps operating under three working conditions.

As the main transmission component of earthmoving machinery, planetary transmission is easy to cause the problem of excessive temperature rise rate because of its compact structure and high power density. Through reliable power loss analysis, this paper quantifies the power loss of the gearbox under various working conditions, determines the power loss body of the gearbox under high-speed and light load conditions, and quickly predicts the oil temperature rise characteristics under different working conditions based on the convective heat transfer mechanism between the box and the outside world. Then, aiming at the high speed and light load condition, a series of engineering optimization scheme for power loss main body is proposed. After bench test, the average no-load power loss and temperature rise rate of the optimized gearbox are reduced by 40% and 59.75% respectively. This paper provides an important reference for solving the problem of thermal instability of transmission in high-speed driving condition of electric construction machinery products.

This study focuses on the subsea CIMV equipment developed by a certain company. Experimental measurement methods were used to investigate the relationship between the differential pressure and the chemical injection volume in the subsea CIMV equipment. By fitting a mathematical formula to the relationship between the differential pressure and the chemical injection volume, a piecewise function with a breakpoint at 0.5427 MPa was obtained. This function allows for the calculation of the real-time injection amount in subsea CIMV equipment based on the real-time differential pressure. The average errors between the calculated values and the actual flow values were 0.0443 L/h and 0.0766 L/h, respectively.

In light of the environmental and resource challenges posed by the growing global reliance on fossil fuels, wind energy has emerged as a pivotal sustainable energy solution. Vertical axis wind turbines (VAWTs) are increasingly recognized as crucial to the future development of wind energy technology, owing to their distinctive advantages. This paper meticulously evaluates the aerodynamic performance of both single and dual VAWTs under co-rotation and counter-rotation configurations, utilizing computational fluid dynamics (CFD) simulations. Additionally, a comparative analysis of the aerodynamic characteristics of single and dual units is conducted across various tip speed ratios (TSRs), employing the control variable method. The findings reveal that the wake dispersion of counter-rotating VAWTs is marginally broader in the transverse direction compared to that of co-rotating configurations, with a more pronounced flow acceleration effect observed at the gap. As the TSR increases, the wake recovers more swiftly, and the wind acceleration at the gap is enhanced, albeit within a more confined region. The optimization of TSR is thus identified as essential for boosting the power output of VAWTs and enhancing the wake recovery. These insights are instrumental in guiding the design refinement of VAWTs, optimizing the layout of wind farms, and advancing the implementation of wind energy technologies in both urban and offshore environments.

Aiming at the erosion wear problem with blackwater valve in coal chemical pipeline system, taking V-type regulating ball valve as the research object, based on computational fluid dynamics (CFD) and erosion wear theory, the erosion wear numerical simulation of V-type ball valve was carried out. The distributive law of flow velocity, pressure and erosion morphology in the fluid domain of V-type ball valve is obtained, and compared with the engineering failure valve. The results show that there is obvious negative pressure in the V-type ball valve under the condition of small opening, and the negative pressure value is much lower than the saturated vapor pressure of blackwater at 170 ℃, and the valve is prone to flow cavitation. Under the typical adjustment opening condition, the flow channel upstream surface in the ball body forms an obvious target-like high-pressure area due to the high-speed jet of the V port. Under the high-frequency erosion of the solid medium, the target-like high-pressure area is prone to obvious wear pits. The serious wear area of V-type ball valve is mainly distributed in the front seat of the valve, the upstream surface of the flow channel in the ball body, the valve body and the rear seat of the valve. When the sealing pair area of the valve seat is seriously scoured and worn by particles, it is easy to cause sealing failure. In addition, the maximum wear rate and average wear rate of the valve wall gradually decrease with the increase of the opening degree. When the relative opening degree is greater than 40%, the wear rate is significantly reduced. In order to prolong the service life of the valve, the V-type ball valve should be reduced to work at a small opening degree.

The reliable operation of the subway drainage system is crucial to the security of various subway systems. Conducting reliability evaluation on the key equipment of the subway drainage system, the submersible sewage pump, can provide support for the intelligent maintenance decision-making of the subway drainage system. Considering the multiple failure modes of the submersible sewage pump in subway drainage, the failure of the mechanical seal of the submersible sewage pump is described using a degradation failure process and modeled using a Wiener process. Meanwhile, for the sudden failure time of the submersible sewage pump, a Weibull model is used for fitting. The reliability model under the competitive relationship of degradation failure and sudden failure is established by combining the performance degradation data and sudden failure data of the pump, and the reliability evaluation of the pump is completed under different failure conditions. Finally, the simulation analysis verifies that the model can effectively and accurately evaluate the reliability of the pump.

Hydrogen is a flammable and explosive gas, and the extraction, transportation, and storage of hydrogen cannot be separated from the hydrogen transportation control system. Axial flow control valves (also known as control valves) are important control nodes in the hydrogen transportation control system, playing a crucial role in the connection, regulation, and cut-off of hydrogen transportation, as well as ensuring the safety of the entire transportation control process. The paper analyzed the product structure of axial flow control valves for hydrogen transmission and studied the influence of design specific pressure on the sealing performance of axial flow control valves for hydrogen transmission and control; The size of the balanced sealing ring was provided and experimental verification was carried out, the results showed that the sealing performance of the prototype was safe and reliable, meeting the requirements of industrial standards, and the safety and localization replacement of axial flow control valves in hydrogen extraction, transmission control, storage and transportation processes are achieved.

This paper proposes an energy-saving control scheme for a dust suppression vehicle in the context of energy conservation and emission reduction. Starting from the global matching of the engine-hydraulic system-load, this scheme analyzes the high-efficiency working interval of the variable pump and variable motor based on the mapping data analysis of the hydraulic system and load. In addition, the engine's fuel economy zone is analyzed based on its performance characteristics curve. On the basis of analyzing the high-efficiency zone of the hydraulic system and the fuel economy zone of the engine, a comprehensive matching energy-saving control scheme for the dust suppression vehicle is proposed. Finally, field tests on the dust suppression vehicle with the proposed energy-saving system were conducted, and the test data showed that the dust suppression vehicle with this energy-saving system saves 50% energy compared to the previous method, while improving system stability. The proposed scheme can provide a reference for other engineering machinery.

In response to the situation which some hydraulic cylinders can only use asymmetric structures but require closed systems, a symmetrical pump driven asymmetric hydraulic cylinder system scheme is proposed, which is to design a flow balance system on top of the conventional closed system structure. The scheme is designed, calculated, and simulated to obtain the static and dynamic characteristics of the system. And it has provided for the instantaneous suction problem which occurring in dynamic characteristics, and it has verified through actual machine testing.

As an important power transmission and control mode, hydraulic system is widely used in various fields. As the key component in the hydraulic system, servo valves play the role of regulating and controlling hydraulic oil, and accumulators are energy storage and release devices in hydraulic system. In some special application occasions, the combination of large-flow servo valves and the accumulator can form a high-power hydraulic system for high-speed response. And whether the two key and important component combinations of the servo valve and the accumulator can meet the system's demand for time and energy, by calculating and analyzing the characteristics of the servo valve's high flow rate and the energy release characteristics of the accumulator on the test bench, it was found that the pressure drop after the accumulator releases energy is 8.8%, and the action time of the servo valve is 0.09 s, which meets the test requirements of the hydraulic system.

During the variable speed load period, the hydraulic rolling bearings of the coal preparation belt machine showed significant propeller blade frequency excitation. Therefore, when analyzing the fault response characteristics of its measuring points, it is necessary to consider the unique dynamic characteristics formed by the variable speed excitation characterization under the vibration transmission effect, and establish a mapping relationship between typical faults and dynamic response characteristics in vibration signals, which is a necessary prerequisite for accurate fault diagnosis. To this end, a thorough analysis of the dynamic changes of faulty hydraulic rolling bearings under variable speed conditions is needed. Extract the vibration signal characteristics of hydraulic rolling bearings under variable speed operating conditions, obtain the variable speed load excitation period of the hydraulic rolling bearings, obtain the natural resonance frequency of the faulty bearing, quantify the fault characteristics of the hydraulic rolling bearings, obtain the estimated time-frequency ridge of the fault vibration signal, and the instantaneous frequency of the corresponding fault vibration signal. Based on the quantified instantaneous frequency of hydraulic rolling bearing characteristics and the corresponding instantaneous frequency of fault vibration signals, corresponding dynamic characteristic responses are established under non defect and defect conditions, respectively. Through experiments, it has been found that the larger the fault, the richer the corresponding dynamic impact characteristics are expressed, and the more the impact response is.

The aircraft hydraulic system has high pollution requirements. If the pollution exceeds the standard requirements, it will lead to the loss of functions such as clamping and sliding of the hydraulic system accessories, resulting in the failure of the hydraulic system. Therefore, the oil filter is set in the hydraulic system, and the off-pressure oil filter is arranged on the high-pressure line of the hydraulic system to the filter out impurities in the high-pressure pipeline. The high-pressure oil filter inlet and outlet connection pipe, the joint is straight screwed in, the joint is set in the rubber ring, to ensure that the sealing can be reliable under high pressure. But during the aircraft repair stage, it is found that due to the wear of the high-pressure oil filter thread, pressure impact and other reasons, the high-pressure oil filter thread and the joint thread clearance becomes larger, which also leads to the sealing gap becomes larger, and the rubber ring is extrusion-ground into powder from the gap, which resulting in seal failure and hydraulic system failure analysis. This will affect the completion of aircraft missions and flight safety. This paper studies the conventional seal failure analysis, improves and validates the seal structure, improves the seal reliability, and ensures the safety of hydraulic system and aircraft.

The hydraulic system of the underwater control module in oil fields is exposed to high pressure, high temperature, and corrosive environments for a long time, facing extremely high risk of failure. Therefore, in order to effectively diagnose and prevent maintenance of hydraulic systems, a fault diagnosis model for hydraulic systems will be constructed based on dynamic Bayesian networks. The experimental results indicate that both the historical failure probability of the hydraulic system and the predicted failure probability value increase with time. At T=0, the predicted hydraulic system failure probability value is 0.106, which is very close to the historical hydraulic system failure probability of 0.117. At T=20, the predicted failure probability is 0.194 and the historical failure probability is 0.198, with a slight increase in the difference in diagnostic probability between the two. In addition, from T=0 to T=20, the accuracy of model fault diagnosis is above 85%, with the highest prediction accuracy of 96.2% at T=0 and the lowest prediction accuracy of 85.7% at T=20. Research has shown that the proposed diagnostic model has good accuracy and stability in fault diagnosis, providing a new solution for intelligent fault diagnosis of SCM hydraulic systems in oil fields.

This paper analyzes the cause of failure of the normal braking function caused by decompression valve failure,which led to the aircraft crashing off the runway.Based on mechanism analysis,experimental verification,theoretical calculation,and other methods,an optimization plan is proposed to effectively reduce the occurrence of faults under existing structures.It is proposed that human control forces are relatively small compared to electromagnetic and hydraulic forces,and the adaptation frequency of valves that require human control in the hydraulic system should be increased to avoid accumulation of attachments and serious consequences caused by long-term non operation.

A new self-locking hydraulic pipe clamp are designed by combining with practical needs of steelmaking process. Ratchet and pawl are used to fasten the screw of the clamp, to prevent the looseness from the working condition of large impact and vibration load from hydraulic pipe. After the new clamp was put into use, the malfunction from looseness of clamp almost entirely prevented, and maintenance frequency reduces significantly, which achieve the effect of stable production and create a huge amount of economic benefits. Construct validity of the self-locking hydraulic pipe clamp is verified by Autodesk Inventor simulation that it could absolutely meet the needs of field production.

Aiming at the issues of heavy workload and low efficiency in test data processing during hydraulic pump efficiency testing, an automated data processing method based on the zero-pressure intercept method was proposed. During the experiment, pressure and temperature compensation were applied to flow measurements, with error points eliminated using the least squares method. A MATLAB algorithm implementing this methodology was subsequently developed. The research demonstrates that the exclusion of error points enables high-precision measurement of no-load displacement, while the application of the MATLAB algorithm significantly improves testing efficiency for pump no-load displacement. Furthermore, the integrated approach of compensation and error elimination enhances the overall reliability of hydraulic pump performance evaluation.