Hydraulic Research Articles

Development of a Prototype Hydraulic Damping Device for Hot Water Heating Circuit in Pulse Mode

This paper provides a comprehensive exploration into the design and implementation of the hydraulic damping device within a pulse mode hot water heating loop. It outlines a systematic approach aimed at optimizing system performance, detailing the operational principles of the pulse mode heating circuit and presenting a structured construction scheme for the hydraulic damping apparatus. Accompanying this analysis is a simplified diagram illustrating the hydraulic damping system, offering a clear visual representation of its integration within the heating circuit. Through mathematical transformations, essential parameters such as complex impedance, frequency function, and vibration frequency characteristics are derived, providing valuable insights into the dynamic behavior of the system. Culminating this investigation, the paper constructs the frequency response of the circuit, offering a comprehensive understanding of its dynamic behavior across varying frequencies. This synthesis of theoretical frameworks and practical applications advances our understanding of pulse mode hot water heating technology, paving the way for enhanced efficiency and performance in heating systems.

Structure optimization design approach of friction pairs for low-temperature rise wet brake in hydraulic motor

Cam-lobe radial-piston hydraulic motors are widely used in large heavy-duty machinery as direct-drive components of hydraulic systems. Due to their extremely high output torque and power density, the wet brake equipped with the hydraulic motors are necessary to achieve ultra-high braking torque in a compact space. However, due to a large number of internal friction pairs and small fit clearance between multiple friction pairs in wet brake, the rotation of the friction pairs in non-braking state will cause large friction torque loss and obvious temperature rise, thereby leading to the thermal failure of wet brake. How to optimize the structure of friction pairs to reduce the temperature rise of wet brake in non-braking state is a persistent challenge. Existing structure optimization design approaches of friction pairs in brakes mainly focus on the structure of each friction pair, which ignore the effect of fit clearance between the friction pairs on the temperature rise of brakes. Nevertheless, the fit clearance between friction pairs is an important factor that affect the temperature rise. For that, this study proposes a two-step structure optimization design approach of friction pairs for low-temperature rise wet brake in hydraculic motor, which simultaneously considers the fit clearance between the friction pairs and the structure of each friction pair. In this approach, the design process could be divided into two steps: firstly, the influence of fit clearance between multiple friction pairs on the temperature rise of wet brake in non-braking state is analyzed and optimized by the temperature rise theoretical model; secondly, in order to further reduce the temperature rise of wet brake, the oil groove structure of each friction plate are introduced and optimized by fluid-solid-thermal coupling simulation method. By this approach, the low-temperature rise structure of friction pairs with the optimized fit clearance between multiple friction pairs and oil grooves of each friction plate. Finally, a series of experiments are conducted to verify the effectiveness of the design approach. The result show that the temperature rise of wet brake could be effectively reduced 12 % by optimizing the structure of wet brake, demonstrating that the structure optimization design approach could provide a theoretical guidance to design low-temperature rise wet brake for large torque hydraulic motors.

Effect of changes in hydraulic parameters and tank capacity of the hydraulic press system on the heating of the hydraulic oil

This study examines the influence of altering hydraulic parameters on the temperature of ISO HM VG 46 hydraulic mineral oil. Hydraulic mineral oils find extensive application in industrial power transmission systems, where precise temperature control is crucial for achieving optimal performance and prolonging system lifespan. Variations in hydraulic parameters, encompassing flow rate, pressure, and viscosity, can significantly impact the thermal characteristics of hydraulic oil.In this research, experimental studies were carried out to study the influence of changing hydraulic parameters on the temperature of hydraulic mineral oil. Experiments were performed on a hydraulic press, where different working conditions were simulated.The quality of hydraulic fluid is considered, according to all research, to be the most influential factor in ensuring the reliable operation of hydraulic systems.

Simulation and analysis of the electro-hydraulic coordinated system for the disc brake system in mining belt conveyor

The present study aims to investigate the dynamic performance of the disk hydraulic brake system in a mining belt conveyor. To achieve this, a simulation model of the hydraulic system for the belt conveyor is designed and constructed using AMESim. It is recognized that brake disk deformation can lead to brake shock, thus an ADAMS rigid-flexible coupling model for hydraulic disk brakes is established. Furthermore, the concept of rigid-flexible coupling mechanical systems is introduced into the hydraulic system to enable interaction between physical quantities. Use fuzzy logic rules to adjust parameters in Simulink, and in response to the suboptimal control of braking and acceleration, a compact non-model-based adaptive algorithm is incorporated into the conventional PID control algorithm. Employing mechanical modeling and multidisciplinary dynamic collaborative simulation technology, a simulation system integrating electromechanical and hydraulic aspects is developed for the disk hydraulic brake of belt conveyors. This system is employed to conduct simulation studies on the closed-loop control of braking disk speed and deceleration/acceleration for belt conveyors. The study findings reveal that the non-model-based adaptive PID control algorithm, in comparison to fuzzy PID, not only demonstrates quicker and more stable responses across various dynamic performance curves but also markedly reduces the axial oscillation amplitude of the braking disk under braking conditions.

Design and Simulation of Intra-Row Obstacle Avoidance Shovel-Type Weeding Machine in Orchard

This paper presents the design of an intra-row obstacle avoidance shovel-type weeding machine. Theoretical analysis of intra-row weeding components guided the determination of the structures and parameters for key parts, including the signal acquisition mechanism, automatic obstacle avoidance mechanism, and weeding shovel. Furthermore, a hydraulic system was designed to support these functions. The design aims to optimize intra-row weeding operations, reduce labor costs, enhance weed control effectiveness, and prevent collisions between weeding equipment and grapevines. Through the construction of a mathematical model, the analysis determined the necessary minimum return speed of the hydraulic cylinder for the intra-row weeding shovel to avoid grapevines. We also established a reasonable range for the extension speed of the hydraulic cylinder to minimize areas missed during weeding. Further analysis showed that using the minimum return speed of the hydraulic cylinder effectively reduced missed weeding areas. A virtual prototype model of the weeding machine was created in ADAMS. Using the coverage rate of weeding operation as the evaluation index, single-factor simulation tests determined that the extension speed of the piston rod in the obstacle avoidance hydraulic cylinder and the forward speed of the weeding machine are the main influencing factors. The preset threshold of the control system, which triggered the automatic obstacle avoidance mechanism when the obstacle avoidance rod reached a specific angle (the “Angle Threshold”), was identified as a secondary influencing factor. Other factors were considered irrelevant. Hydraulic cylinder extension speed, weeding machine forward speed, and angle threshold were chosen as the influencing factors. Following the principles of a Box–Behnken experimental design, a quadratic regression combination experiment was designed using a three-factor, three-level response surface analysis method. The evaluation criterion focused on the coverage rate of weeding operation. A regression model was developed to determine the coverage rate of the weeding operation, identifying the optimal parameters as follows: obstacle avoidance hydraulic cylinder extension speed of 120 mm/s, forward speed of the weeding machine at 0.6 m/s, and an angle threshold of 18°. The optimized coverage rate of the weeding operation achieved 86.1%. This study serves as a reference for further optimization of intra-row weeding machines in vineyards and for other crops.

Multifractal Characterization of Coal Deterioration Induced by Cyclic Hydraulic Pressure Based on the Acoustic Emission Test and X-ray Microscopy

Multifractal Characterization of Coal Deterioration Induced by Cyclic Hydraulic Pressure Based on the Acoustic Emission Test and X-ray Microscopy

Comparative analysis of microdamage-affected chloride transport in concrete under static and dynamic hydraulic pressure

Concrete structures in marine environments frequently encounter the adverse impacts of hydraulic pressure, leading to a decrease in their durability. This study aims to conduct a comparative analysis of the internal microdamage in concrete when subjected to static and dynamic hydraulic pressure of equal intensity, and to examine the influence of such damage on chloride transport. By employing potentiometric titration, MIP, N2 adsorption, and AFM tests, the chloride concentration, pore structure parameters, and microscale elastic modulus of concrete under static and dynamic hydraulic pressure were analyzed. The results indicate that dynamic hydraulic pressure accelerates chloride transport in concrete. Compared with static hydraulic pressure, dynamic hydraulic pressure — sustained at the same intensity—results in an elevated threshold pore size along with an increased most probable pore size of the concrete. Furthermore, dynamic hydraulic pressure induces the expansion of microcracks, consequently decreasing the microscale elastic modulus of concrete. The use of mineral admixtures can effectively mitigate the damage evolution of concrete microstructure subjected to dynamic hydraulic pressure. Besides, a model is developed for relative chloride diffusion based on the principle of energy conservation and from the evolution law of the microscale elastic modulus gleaned from AFM tests. Through calculations, it can be found that the crack propagation rate and the decline rate of the relative chloride diffusion coefficient Df1Df2 increase markedly when dynamic hydraulic pressure intensity surpasses 40,000 Pa. The propagation of the crack length is moderated by a larger initial crack width.

Experimental analysis of instability and self-oscillations in an electrohydraulic servo drive

The tendency to self-oscillations is one of the most important problems of closed-loop hydraulic systems. In actual systems losses occur, variation of the transmitted energy and the strength of the system structural elements are always limited. This is the reason why self-oscillations are most often present. The main purpose of the research is to reveal the mechanisms of instability and self-oscillations in an electro-hydraulic servo drive to make a numerical simulation of the drive characteristics. A servo drive has all the conditions for the generation of self-oscillations: the oscillatory element – the movable member of the drive and a column of elastic liquid, the source of energy. Regular oscillations in a drive are maintained due to the energy of compressed liquid, feedback, non-linear character of generated and absorbed energy etc. An experimental analysis of a servo system of the FESTO training simulator was carried out. The aim of the research was to accumulate materials for the development of mathematical models that would adequately represent the main properties of actual systems.

Performance investigation of a novel free piston Stirling pump for reverse osmosis desalination systems

Renewable energy (RE)-powered desalination technology is considered a cleaner and promising alternative for alleviating energy exhaustion and environmental pollution resulting from traditional desalination. Currently available solar thermal reverse osmosis (RO) desalination systems are based on the organic Rankine cycle. With the aim to expand the driving mode of reverse osmosis desalination as well as simplify the transmission chain and reduce mechanical energy losses, a novel hydraulic free piston Stirling pump (FPSP) is developed and a simple model is designed and tested for conceptual validation. A free piston Stirling pump - powered reverse osmosis desalination system is presented, and a thermodynamic–dynamic coupling model is established. A parametric analysis is performed with an emphasis on the effects of temperatures, charge pressure, spring stiffnesses, damping coefficients, and masses on the system performance, including the frequency, power output, water yield, and efficiency. Results showed that the frequency in the pumping process was higher than that in the suction process because of the different loads. Within the range investigated, the performance improved as the hot-end temperature, charge pressure, spring stiffnesses, and damping coefficient of the power piston increased, while it deteriorated with a decrease in the damping coefficient of the displacer and the piston masses. Specifically, the power output and water yield reached the optimum value as the cold-end temperature was maintained around 310 K. Under representative parameter conditions, the power output could reach 12.15 kW and the water yield was approximately 6.07 × 10−4 m3/s. In addition, the temperatures and charge pressure influence the system efficiency most.

Design of a Stormwater Management System in Lady Irene Campus

This project aimed to design an efficient drainage system for Ndejje University's Lady Irene Campus, addressing issues of erosion and flooding exacerbated by recent construction projects. The goal was to create a hydraulic conveyance system that balances environmental protection with structural integrity and affordability. The project involved field reconnaissance, data collection, and analysis of the campus's landscape, soil types, and development trends to inform the design. Methodologically, the project used GPS surveying to create topographical maps and obtained rainfall data to size drainage facilities using the rational method. The peak runoff was calculated considering land use characteristics, while Manning’s formula was applied to design drainage channels and culverts. The design aimed to ensure high hydraulic capacity and prevent erosion with specific slope and material choices. An Environmental Impact Assessment was conducted, addressing noise, dust, water quality, waste management, and ecological impacts. Mitigation measures were recommended to minimize adverse effects during the construction and operation phases. Despite challenges such as limited access to surveying equipment and data, the project concluded with a comprehensive stormwater management plan. Recommendations include rehabilitating the university’s weather station and establishing a project database to support future planning and research. The project underscores the importance of integrating sustainable practices in urban development to safeguard environmental and infrastructural integrity.

A novel optimization model for tackling capacity challenges in natural gas gathering systems

In the layout optimization of natural gas gathering pipeline network, a lot of work has been done, but few scholars focus on the capacity optimization of gas gathering station (short for station). The structural relationship parameters of dendritic pipeline network and the flow parameters of pipeline network are complicated, which makes it difficult to establish the model, and at the same time, the existence of nonlinear term causes the difficulty of solving the problem. In the current two stage star-dendritic natural gas gathering pipeline network, pipeline sizes and station capacity are not well taken into account for the optimization of pipeline network layout at the same time. In this paper, a consideration station capacity and pipeline sizes: Two-stage star-dendritic network layout optimization model (SCPSTSDLO-Model) is constructed by integrating the factors of site discrete characteristics, station capacity and pipeline sizes, and considering the hydraulic pressure drop conditions of the network, and a solution framework based on the nonlinear processing is proposed, which can obtain the optimization results of optimal affiliation, station type, station site and pipeline sizes at the same time. Five cases are used to verify the validity and accuracy of the model and algorithm, compare the sensitivity analysis and solution algorithm, compare the hydraulic pressure drop conditions, and analyze the application in different forms of pipeline networks. The results show that the SCPSTSDLO-Model and the solution method established in this paper can obtain the optimal solutions under different topologies according to the application requirements, taking into account the capacity of stations and pipeline sizes.

Hydraulic system fault diagnosis decoupling method based on 2D time-series modeling and self-attention fusion

Hydraulic systems play a pivotal and extensive role in mechanics and energy. However, the performance of intelligent fault diagnosis models for multiple components is often hindered by the complexity, variability, strong hermeticity, intricate structures, and fault concealment in real-world conditions. This study proposes a new approach for hydraulic fault diagnosis that leverages 2D temporal modeling and attention mechanisms for decoupling compound faults and extracting features from multisample rate sensor data. Initially, to address the issue of oversampling in some high-frequency sensors within the dataset, variable frequency data sampling is employed during the data preprocessing stage to resample redundant data. Subsequently, two-dimensional convolution simultaneously captures both the instantaneous and long-term features of the sensor signals for the coupling signals of hydraulic system sensors. Lastly, to address the challenge of feature fusion with multisample rate sensor data, where direct merging of features through maximum or average pooling might dilute crucial information, a feature fusion and decoupling method based on a probabilistic sparse self-attention mechanism is designed, avoiding the issue of long-tail distribution in multisample rate sensor data. Experimental validation showed that the proposed model can effectively utilize samples to achieve accurate fault decoupling and classification for different components, achieving a diagnostic accuracy exceeding 97% and demonstrating robust performance in hydraulic system fault diagnosis under noise conditions.

Research of Oscillations Processes in the Hydraulic System of Liquid Droplet Radiator

Research of Oscillations Processes in the Hydraulic System of Liquid Droplet Radiator

Analysis and Development of an IoT System for an Agrivoltaics Plant

This article illustrates the development of SolarFertigation (SF), an IoT (Internet of Things) solution for precision agriculture. Contrary to similar systems on the market, SolarFertigation can monitor and optimize fertigation autonomously, based on the analysis of data collected through the cloud. The system is made up of two main components: the central unit, which enables the precise deployment and distribution of water and fertilizers in different areas of the agricultural field, and the sensor node, which oversees collecting environmental and soil data. This article delves into the evolution of the system, focusing on structural and architectural changes to develop an infrastructure suitable for implementing a predictive model based on artificial intelligence and big data. Aspects concerning both the sensor node, such as energy management, accuracy of solar radiation readings, and qualitative soil moisture measurements, as well as implementations to the hydraulic system and the control and monitoring system of the central unit, are explored. This article provides an overview of the results obtained from solar radiation and soil moisture measurements. In addition, the results of an experimental campaign, in which 300 salad plants were grown using the SolarFertigation system in a photovoltaic field, are presented. This study demonstrated the effectiveness and applicability of the system under real-world conditions and highlighted its potential in optimizing resources and increasing agricultural productivity, especially in agrivoltaic settings.

Stability and stabilization for the hydraulic automatic gauge control system of cold rolling mill with time delay and saturation

This paper studies the stability and stabilization of hydraulic automatic gauge control (HAGC) systems with time-varying delay and actuator saturation. First, a mathematical model of HAGC systems is established considering the measurement delay and saturation factors. With the help of state transformation, the measurement delay is transformed into input delay and the generalized sector condition is adopted to deal with the saturation problem in HAGC systems. Then, a new augmented L–K functional is constructed to contain more delay information to reduce the conservativeness of the stability criteria. Furthermore, by combining the proposed L–K functional with some advanced inequalities, the stability conditions and controller are derived with the aid of linear matrix inequalities (LMIs). Finally, the effectiveness of the proposed control algorithm is verified by simulation results.

Research on the design and optimal control of the power take-off (PTO) system for underwater eel-type power generators

Wave energy and ocean current energy are considered stable, reliable, and highly predictable renewable energy sources. The development of ocean current energy conversion technology is crucial in addressing power shortages. However, the low velocity of most ocean currents worldwide, typically less than 1.5 m/s, poses a challenge for traditional ocean current energy capture devices. Current estimations of power generation from underwater devices often significantly differ from actual results. This study presents an eel-type power generation device designed for underwater use, investigates the design and optimization of a hydraulic power take-off (PTO) system suitable for such devices, and examines key components of the hydraulic PTO system like variable hydraulic motors and generators. Analytical research was conducted to understand its operational characteristics, with a focus on components such as the accumulator, speed control valve, and energy storage flywheel. The article also delves into the hydrodynamic and energy conversion characteristics of the device under shallow water wave and current conditions, enhancing the hydraulic PTO system model and establishing an integrated calculation model for real-time data transmission during the calculation process. Through evaluations of pitch angle and power generation under varying sea conditions, the study explores the impact of hydraulic motor displacement and damping coefficient on the hydrodynamic and power generation characteristics of the device, further validated through sea trials. The study findings indicate a high level of parameter adaptation among the components of the hydraulic system. The addition of an accumulator to the system results in smoother output response curves, suggesting that the accumulator absorbs impacts and stabilizes the hydraulic power transmission system. The proposed comprehensive calculation method enables a more precise prediction of the performance of the eel power generation device in real marine environments, capturing its movement behavior and power generation characteristics. Adjusting the motor displacement or damping coefficient under specific conditions can optimize the total damping of the hydraulic PTO system for maximum power output. The optimal power point of the hydraulic power generation system varies for different sea conditions, with a potential power generation efficiency of up to 80.3% under certain circumstances.

USAGE OF TECHNICAL MEANS FOR ANNULAR GAS EXTRACTION TO INCREASE OIL WELL PRODUCTION

In recent years, the technology of annular gas extraction from wells has become increasingly widespread in the fields in order to improve the working conditions of the submersible pump due to increasing its filling and supply coefficients, as well as increasing depression on the formation. Some types of compressor designs have been developed and put into production, allowing the annular gas extraction from wells and forced injection into the pressure line of the well. One of the most well-known types of compressors is a piston pair driven by a piston from a rocking machine balancer. They were used at oil production facilities in the Orenburg, Ulyanovsk Regions, the Republics of Tatarstan and Bashkortostan, Udmurtia and other regions of the Russian Federation.In the fields of Sheshmaoil LLC, a complex for pumping gas from the annulus of a well and pumping it into the COGS product collection system has found mass usage, allowing gas to be taken from a group of wells and reducing pressure in the annulus to values close to 0.1 MPa. Hydraulic piston compressors, in which gas compression occurs using a high-pressure pump that drives the piston group of the compressor, have been tested.One of the main disadvantages of the developed types of compressors is the insufficient volume and pressure of the compressed gas. The article provides an analysis of the technological parameters of the compressors. As a result of research possible solutions to the problem are worked out.To achieve the largest pumping volumes of separated annular gas, the maximum permissible diameter of the compressor cylinder should not exceed 0.07 m in order to prevent significant resistance exerted by the piston rod on the balancer of the pumping machine.The most suitable region for the effective use of suspended compressors is the Ural-Volga Region at fairly depleted oil fields with at least 60–65 % water cut, oil well flow rate of no more than 10–15 tons/day and a gas factor of no more than 15–20 m3/t . At the fields of Western Siberia, suspended compressors cannot be used due to high flow rates and gas factors. Exceptions may be wells with a water cut of at least 80 % and flow rates of no more than 20–25 tons/day.The KOGS compressor unit, developed and widely implemented at Sheshmaoil Management Company LLC, showed positive results, consisting of an increase in flow rate and additional oil production. For further use of the unit in fields, especially for high-viscosity oil production, as well as operation in winter conditions, it is necessary to increase the maximum gas injection pressure.

Resistance Analysis of Crack Propagation in Concrete Subjected to Hydraulic Pressure.

The KR resistance curve for hydraulic crack propagation in a concrete beam was determined and discussed. A semi-analytical method was introduced to calculate the hydraulic crack propagation in concrete. A series of concrete beams with various hydraulic pressures and initial crack depths were tested, and the hydraulic crack propagation in these beams was calculated. The calculated P-CMOD curves were first verified, and then the calculated KR resistance curve for hydraulic crack propagation was determined. Based on the test results and calculation results, the following conclusions can be drawn: The proposed analysis method can accurately predict the hydraulic crack propagation process in concrete. The KR resistance to hydraulic crack propagation in concrete decreases with the increase in hydraulic pressure but is less influenced by the initial crack depth of the test beams. In addition, the concrete beams collapse immediately under hydraulic fracturing once the KIw curve reaches the KR resistance curve. This indicates that the failure of concrete structures under hydraulic fracturing occurs immediately once the driving force of crack propagation, dominated by the hydraulic pressure in the crack, becomes significant.

Predictive control of linear time-varying model for hydraulic erecting systems based on linear expanded state observer

By analyzing the deficiencies of existing hydraulic erecting systems (HESs) control methods, this study proposes a linear time-varying model predictive control (LTV-MPC) method based on the linear extended state observer (LESO) for HESs. First, the working mechanism of HESs is methodically analyzed and the corresponding state space equations are established. Second, the LESO system is designed to estimate the current unknown real-time states. Then, the LTV-MPC is employed to evaluate and output the optimal solution of the servo voltage signal. Finally, through simulation and experiment, the effectiveness of the proposed method is confirmed and discussed. The results show that the displacement error rate of the proposed method is still lower than 0.223% under larger external disturbances, which can effectively improve the control accuracy and stability of the system compared with other methods.

Investigation of the impact of surface roughness on the flow characteristics of a broad-crested weir

ABSTRACT Weirs are a common hydraulic structure. The broad-crested weir's effectiveness depends on its height and surface roughness. The present study investigates the coefficient of discharge (Cd) for various broad-crested weirs in a laboratory flume. Two types of weir geometry were used and outfitted with three types of surface roughness (cement, boulders, and gravel) and the coefficient of discharge. The outcomes showed that the coefficient of discharge reduces as the surface roughness of the broad-crested weir increases for a given (H/H + P). The average value of the discharge coefficient for Group 1 (models 1, 2, and 3) was 0.66, 0.65, and 0.64, respectively. For comparison between models 1 and 2 and between models 1 and 3, the decrease in the coefficient of discharge was approximately 2 and 3.5%, respectively. Group 2 (models 4, 5, and 6) had an average value of the discharge coefficient of 0.63, 0.62, and 0.61, respectively. The decrease in the coefficient of discharge for comparison between models 4 and 5 and between models 4 and 6 was around 1.75 and 3%, respectively. Empirical equations were obtained to accurately fit the data. This study can inform the design of weirs, allowing for improved control and flow regulation in hydraulic systems.