Hydraulic Research Articles

On the possible use of hydraulic force to assist with building the step pyramid of saqqara.

The Step Pyramid of Djoser in Saqqara, Egypt, is considered the oldest of the seven monumental pyramids built about 4,500 years ago. From transdisciplinary analysis, it was discovered that a hydraulic lift may have been used to build the pyramid. Based on our mapping of the nearby watersheds, we show that one of the unexplained massive Saqqara structures, the Gisr el-Mudir enclosure, has the features of a check dam with the intent to trap sediment and water. The topography beyond the dam suggests a possible ephemeral lake west of the Djoser complex and water flow inside the 'Dry Moat' surrounding it. In the southern section of the moat, we show that the monumental linear rock-cut structure consisting of successive, deep compartments combines the technical requirements of a water treatment facility: a settling basin, a retention basin, and a purification system. Together, the Gisr el-Mudir and the Dry Moat's inner south section work as a unified hydraulic system that improves water quality and regulates flow for practical purposes and human needs. Finally, we identified that the Step Pyramid's internal architecture is consistent with a hydraulic elevation mechanism never reported before. The ancient architects may have raised the stones from the pyramid centre in a volcano fashion using the sediment-free water from the Dry Moat's south section. Ancient Egyptians are famous for their pioneering and mastery of hydraulics through canals for irrigation purposes and barges to transport huge stones. This work opens a new line of research: the use of hydraulic force to erect the massive structures built by Pharaohs.

Scan-to-HBIM-to-VR: An Integrated Approach for the Documentation of an Industrial Archaeology Building

In this paper, we propose a comprehensive and optimised workflow for the documentation and the future maintenance and management of a historical building, integrating the state of the art of different techniques, in the challenging context of industrial archaeology. This approach has been applied to the hydraulic work of the “Sostegno del Battiferro” in Bologna, Italy, an example of built industrial heritage whose construction began in 1439 and remains in active use nowadays to control the Navile canal water flow rate. The initial step was the definition of a 3D topographic frame, including geodetic measurements, which served as a reference for the complete 3D survey integrating Terrestrial Laser Scanning (TLS), Structured Light Projection scanning, and the photogrammetric processing of Unmanned Aircraft System (UAS) imagery through a Structure from Motion (SfM) approach. The resulting 3D point cloud has supported as-built parametric modelling (Scan-to-BIM) with the consequent extraction of plans and sections. Finally, the Heritage/Historic Building Information Modelling (HBIM) model generated was rendered and tested for a VR-based immersive experience. Building Information Modelling (BIM) and virtual reality (VR) applications were tested as a support for the management of the building, the maintenance of the hydraulic system, and the training of qualified technicians. In addition, considering the historical value of the surveyed building, the methodology was also applied for dissemination purposes.

Switching Frequency Improvement of a High Speed on/off Valve Based on Pre-excitation Control Algorithm

The high-speed on/off valve (HSV) serves as the fundamental component responsible for generating discrete fluids within digital hydraulic systems. As the switching frequency of the HSV increases, the properties of the generated discrete fluid approach those of continuous fluids. Therefore, a higher frequency response characteristic of HSV is the key to ensure the control accuracy of digital hydraulic systems. However, the current research mainly focuses on its dynamic performance, but neglect its FRC. This paper presents a theoretical analysis demonstrating that the FRC of the HSV can be enhanced by minimizing its switching time. The maximum switching frequency (MSF) is mainly determined by opening dynamic performance when HSV operates with low switching duty ratio (SDR), whereas the closing dynamic performance limits the MSF when HSV operates with high SDR. Building upon these findings, the pre-excitation control algorithm (PECA) is proposed to reduce the switching time of the HSV, and consequently enhance its FRC. Experimental results demonstrate that PECA shortens the opening delay time of HSV by 1.12 ms, the closing delay time by 2.54 ms, and the closing moving time by 0.47 ms in comparison to the existing advanced control algorithms. As a result, a larger MSF of 417 Hz and a wider controllable SDR range from 20% to 70% were achieved at a switching frequency of 250 Hz. Thus, the proposed PFCA in this paper has been verified as an effective and promising approach for enhancing the control performance of digital hydraulic systems.

Implementing Component Degradations into a Modelica Model of an iPWR System to Develop Health Monitoring Techniques

The economic operation of small modular reactors will partly rely on managing and reducing inspection and maintenance activities while supporting new operational paradigms like load-following. Turbine control valves throttle the steam from the steam generator into the steam turbine while maintaining the pressure within the steam generator at a constant set point. Degradation of these components could impact the ability to manage electrical power production. Utilizing the Idaho National Laboratory Hybrid repository and the Oak Ridge National Laboratory TRANSFORM library developed for multiphysics simulations in Dymola/Modelica, an integral pressurized water reactor system was modeled based on the available specifications of the NuScale power module. The effects of various component degradation modes have been implemented into the model in order to simulate faulted plant data during both steady-state and load-following operations. The fault modes resemble different physical fault modes that may occur at an operating nuclear power plant; a leaking turbine control valve and a valve actuator failure due to loss of hydraulic pressure have been implemented. A neural network autoencoder is employed in conjunction with statistical analysis, namely, simple signal thresholding (SST) or sequential probability ratio testing (SPRT), to identify the presence of a fault. Fuzzy logic is additionally employed in a novel and promising manner to classify the state of the system based on the cumulative sum of the neural network residuals. SST and SPRT are both successfully validated using healthy data and proved capable of identifying both fault types; fuzzy logic identified the false positives and classified the faulted data correctly.

Risk-based method for substantiating reduction of pressure of hydraulic strength tests and its application on steam line of nuclear power plant with WWER (PWR) reactor plant

Hydraulic tests are used in various sectors of the national economy to check the strength and tightness of vessels and pipelines, their parts and assembly units loaded with pressure. The hydraulic test pressure is a calculated value and is determined on the basis of regulatory documentation for the relevant control objects. Analysis of current trends in the field of hydraulic testing both in the Russian Federation and abroad has shown a trend to reduce the damageability of test objects by choosing the most optimal hydraulic test pressure. The main purpose of the research was to reduce the operational damage to equipment and pipelines of nuclear power plants by reducing the pressure of hydraulic strength tests during maintenance. The research is based on probability theory, mathematical statistics, strength physics and fracture mechanics, taking into account the possibility of occasional discontinuities or defects that might be observed in operation. The method is based on a risk-based approach, which makes it possible to determine the permissible risk variation based on recommendations on the safety of nuclear power plants in the Russian Federation. The objects of research are the equipment and pipelines of nuclear power plants. The result of the research is the development of a method substantiating the reduction of the pressure of hydraulic strength tests for equipment and pipelines of nuclear power plants based on a risk-based approach. The developed method can be used by organizations involved in the production of electricity (at nuclear or thermal power plants), transportation of oil, gas or other substances, at facilities where pipelines are an essential part of their structures, affecting the reliability and efficiency of operation of these facilities.

Hydraulic fracture characterization of debris-rich ice hole for polar geological drilling based on Peridynamics

Polar geological drilling is crucial to investigating the earth's environment and climate evolution. Hydraulic fracturing occurs around the ice holes when drilling into the complex debris-rich ice before entering the bedrock. Based on the nonlocal theory, the ice-debris structure is considered in the stability of the borehole wall, and a peridynamics model is developed to explore fracture initiation and propagation characteristics around the debris-rich ice hole. The integrated equation describes the mechanical behavior of ice holes, and the continuous and discontinuous spaces are described uniformly around debris-rich ice holes, avoiding the singularity of local continuum mechanics at the interface and crack tip. In this paper, the separation behavior of the interface is simulated between ice and debris. The cracking propagation process, the influence of debris size and shape, and horizontal pressure are analyzed. The results show that at a hydraulic pressure of 4.0 MPa, 8 radial cracks are initiated from the wall of the ice hole containing circular and elliptical debris, with the final crack volume of 0.66% and 1.40%, respectively. The cracks near the hole wall propagate a circumferential direction after turning or branching, leading to peeling in the ice hole containing elliptical debris with inclination angles of 30° and 60°. Hydraulic pressure balances stress distribution around debris-rich holes when horizontal pressure ranges from 1.2 to 2.4 MPa. When drilling into debris-rich ice formations at different debris and horizontal pressures, it is imperative to adjust promptly the density of drilling fluid. This adjustment aims to regulate the hydraulic pressure within the hole, minimize crack distribution, and ensure safe access to bedrock for coring.

Embolism propagation in Adiantum leaves and in a biomimetic system with constrictions.

Drought poses a significant threat to forest survival worldwide by potentially generating air bubbles that obstruct sap transport within plants' hydraulic systems. However, the detailed mechanism of air entry and propagation at the scale of the veins remains elusive. Building upon a biomimetic model of leaf which we developed, we propose a direct comparison of the air embolism propagation in Adiantum (maidenhair fern) leaves, presented in Brodribb et al. (Brodribb TJ, Bienaimé D, Marmottant P. 2016 Revealing catastrophic failure of leaf networks under stress. Proc. Natl Acad. Sci. USA 113, 4865-4869 (doi:10.1073/pnas.1522569113)) and in our biomimetic leaves. In particular, we evidence that the jerky dynamics of the embolism propagation observed in Adiantum leaves can be recovered through the introduction of micrometric constrictions in the section of our biomimetic veins, mimicking the nanopores present in the bordered pit membranes in real leaves. We show that the intermittency in the propagation can be retrieved by a simple model coupling the variations of pressure induced by the constrictions and the variations of the volume of the compliant microchannels. Our study marks a step with the design of a biomimetic leaf that reproduces particular aspects of embolism propagation in real leaves, using a minimal set of controllable and readily tunable components. This biomimetic leaf constitutes a promising physical analogue and sets the stage for future enhancements to fully embody the unique physical features of embolizing real leaves.

Electro-hydraulic servo position control of bending machine based on Single Neuron PID

Abstract Due to the fixed parameters, inadequate dynamic performance, and significant tracking error of the traditional PID control algorithm, it is challenging to satisfy the increasingly stringent precision demands for position control of the slider in the hydraulic servo system of the bending machine. Given the significant impact of external load on the position accuracy of the bending machine’s slider, a single neuron network is employed to dynamically adjust parameters in response to external load interference, thereby compensating for the limitations of traditional algorithms. Consequently, this paper proposes the design of a single neuron PID (SN-PID) controller to enhance system control accuracy. Through multiple simulation comparisons, it is evident that the SN-PID controller system exhibits superior anti-interference capabilities, enhanced adaptability, and reduced following error compared to traditional PID control algorithms in achieving slider position accuracy.

Characterization of Position Synchronous Control System for Double Hydraulic Cylinder

Background: There are some problems in the synchronous control system of electrohydraulic servo double hydraulic cylinders, such as uncertainty of system parameters, time variation, difference between two subsystems, and unbalanced load disturbance during operation. The above problems cause the output responses of the two cylinders to be inconsistent, resulting in the situation that the output flows of the two cylinders are not synchronized. Objective: Further improve the accuracy of synchronous control while reducing the cost of using synchronous control system. Methods: The AMEsim simulation model of electro-hydraulic servo dual-cylinder synchronous control system is established, and based on this model, the dynamic characteristics, coupling characteristics, and synchronization characteristics of the double-cylinder system are analyzed theoretically and simulated. Results: Analyze and verify the influence of various factors on the synchronization of double hydraulic cylinders, and summarize the influence law of the change of different factors on the output and synchronization accuracy of the double hydraulic cylinder system. Conclusion: This study analyzes the influence of various factors on the synchronization of double cylinders by adjusting the parameters, and summarizes the influence law of the change of different factors on the output and synchronization accuracy of the double cylinder system.

Frequency-domain analysis of fluid-structure interaction in aircraft hydraulic pipeline systems: numerical and experimental studies

Frequency-domain analysis of fluid-structure interaction in aircraft hydraulic pipeline systems: numerical and experimental studies

Detecting Vegetation Stress in Mixed Forest Ecosystems Through the Joint Use of Tree‐Water Monitoring and Land Surface Modeling

AbstractRecent European heatwaves have significantly impacted forest ecosystems, leading to increased plant water stress. Advances in land surface models aim to improve the representation of vegetation drought responses by incorporating plant hydraulics into the plant functional type (PFT) classification system. However, reliance on PFTs may inadequately capture the diverse plant hydraulic traits (PHTs), potentially biasing transpiration and vegetation water stress representations. The detection of vegetation drought stress is further complicated by the mixing of different tree species and forest patches. This study uses the Community Land Model version 5.0 to simulate an experimental mixed‐forest catchment with configurations representing standalone, patched mixed, and fully‐mixed forests. Biome‐generic, PFT‐specific, or species‐specific PHTs are employed. Results emphasize the crucial role of accurately representing mixed forests in reproducing observed vegetation water stress and transpiration fluxes for both broadleaf and needleleaf tree species. The dominant vegetation fraction is a key determinant, influencing aggregated vegetation response patterns. Segregation level in PHT parameterizations shapes differences between observed and simulated transpiration fluxes. Simulated root water potential emerges as a potential metric for detecting vegetation stress periods. However, the model's plant hydraulic system has limitations in reproducing the long‐term effects of extreme weather events on needleleaf tree species. These findings highlight the complexity of modeling mixed forests and underscore the need for improved representation of plant diversity in land surface models to enhance the understanding of vegetation water stress under changing climate conditions.

Numerical modeling of cavity collapse water hammer in pipeline systems: Internal mechanisms and influential factors of transient flow and secondary pressure rise dynamics

This study explores the dynamics of pressure wave propagation and cavitation in pressurized pipelines during and after the rapid closure of the pipeline's end ball valve, utilizing a three-dimensional computational fluid dynamics approach with the method of characteristics, validated against Bergant and Simpson's experimental data of three degrees of cavitation. It innovatively examines transient pressure dynamics through both energy transformation and wave propagation perspectives, focusing on the phases of water column separation and coalescence, and the dynamics of flow interruption bubbles. The research delves into the detailed mechanisms of pressure wave propagation and further assesses the effects of physical factors. Key findings include: (1) As initial inlet velocities increase, cavitation starts earlier, extends further, and intensifies, with higher final volume fractions near the valve, indicating that higher velocities exacerbate cavitation. Higher inlet velocities also correlate with more intricate and expansive vortex formations. (2) Secondary pressure surges in water hammer result from the superposition of two-stage positive pressure waves. Initially, positive pressure waves within the conduit reflect twice from air pockets and the upstream boundary, remaining positive. Subsequently, they interact with secondary positive pressure waves reflected by the valve, causing a secondary pressure surge. (3) The fluid flow is laterally symmetry in the pipe cross section, except for minor local asymmetrical spikes in areas with vapor bubbles. Velocity discrepancies are notable near the pipe walls due to vapor accumulation, primarily on the upper wall due to buoyancy. This accumulation may narrow the flow area, possibly accelerating the water passing by. (4) Lower flow velocities, downward inclines, and slower valve closures diminish secondary pressure rise amplitudes in water hammer events, while reduced static heads intensify cavitation despite lessening pulse amplitudes. These findings offer valuable insights for the design and operational guidance of complex hydraulic systems during transient processes in urban water supplies.

A micro-macro mechanism of hydraulic fracturing with initial stress state effect of brittle rock

The external initial stress state seriously affects the hydraulic fracturing process of rocks. However, the external initial stress effect on the mechanical relationship between the hydraulic pressure and the internal microcrack extension in brittle rocks is rarely studied. This paper proposes a micro-macro mechanical model for predicting the hydraulic fracturing process of brittle rock under compressive stress. Based on the correlation of the stress intensity factor at the tip of the extended micro-cracks, the hydraulic pressure, and the force characteristics of the cracks inside the brittle rock, the evolution law of the hydraulic pressure with the wing crack length is determined. The effects of confining pressure, axial pressure, stress difference, initial crack angle, initial crack length, initial crack density and rock fracture toughness on the hydraulic initiation stress and peak stress are discussed. The rationality of hydraulic fracturing models is verified by experimental comparison. With the increase of axial pressure, stress difference, fracture toughness, initial crack length and initial crack density, the hydraulic initiation and peak stress of rock decrease, and with the increase of confining pressure and fracture toughness, the hydraulic initiation stress and peak stress of rock increase. The study results optimize the parameters such as pre-crack angle, pre-crack length, and external loading conditions based on rock characteristics. It helps to grasp the progress of hydraulic fracturing according to the nature of rock and the degree of hydraulic pressure change, improve the efficiency of hydraulic fracturing, and enhance economic benefits.

Energy characteristics of a deep-sea mining pump under solid-phase interaction

Deep-sea mining pumps (DMPs) are the crucial power equipment for the hydraulic lift deep-sea mining system. The efficiency and sustainability are greatly affected by the particle conveyance capacity and erosion pattern. To investigate the energy performance, particle conveyance capacity, and erosion pattern of the DMP, different inlet particle volume fraction (IPVF) schemes are investigated using the Euler-Euler method. The data indicates that as the IPVF increases, the head and shaft power increase gradually, and the flow rate at the highest efficiency is consistently 1.5Qd. Additionally, the fluctuation range of the conveyance capacity index decreases as the flow rate increases. At an IPVF of 15%, the particles exhibit a backflow phenomenon, resulting in poor particle conveyance capacity. As the flow rate increases, the erosion rate (ER) of the impeller (IMP) decreases and then increases, and the ER of the space guide vane (SGV) gradually decreases, resulting in a more stable flow state. The erosion distribution of the IMP blades is mainly concentrated on the suction surface. The erosion distribution on the SGV blades is primarily concentrated on the middle and rear of the pressure surface, as well as the middle and front of the suction surface.

A Study on the Design of Hydraulic Auxiliary Braking System for Commercial Vehicles

A Study on the Design of Hydraulic Auxiliary Braking System for Commercial Vehicles

Can ozone mass transfer in water treatment be enhanced through independent pressurized ozonation?

The dissolved ozone equilibrium concentration is hard to improve by increasing the gas phase partial pressure due to the low initial pressure and difficulty in pressurization. In this study, a novel hydraulic pressurization technology was developed to reliably elevate the ozonation pressure and improve the solubility of ozone. It was located downstream of the ozone generator to avoid generator overpressure. Specifically, at the optimal pressure of 0.30 MPa with an initial ozone flow rate of 1–6 L min−1, the specific surface area of bubbles and turbulent dissipation rate in the ozonation reactor were up to 2.5- and 1.5-fold that of the atmospheric aeration. Meanwhile, the dissolved ozone equilibrium concentration, redox potential, and volumetric mass transfer coefficient were up to 2.4-, 1.6-, and 2.7-fold that of atmospheric aeration, respectively. The increase in bubble-specific surface area and turbulent dissipation rate, synergistically enhanced the mass transfer, contributing 83.2–94.4 % and 5.6–16.8 %, respectively. As the reactor pressure was increased from 0 to 0.30 MPa, the decolorization time of Acid Red 18 was shortened from 20 to 8 min, and the COD removal rate increased from 48.0 % to 85.0 %. This work provides an alternative approach coupled with a novel device that enhances the ozone mass transfer during water treatment.

New Hydraulic Control Technologies for Improving the Energy Efficiency of the Hydraulic System of Agricultural Tractors and Their Implements

New Hydraulic Control Technologies for Improving the Energy Efficiency of the Hydraulic System of Agricultural Tractors and Their Implements

Submerged surface texturing of AISI 304L using the pulsating water jet method

Submerged jets have a variety of practical applications due to their versatility in providing efficient and environmentally friendly options for treatment in various industries. The physical background is based on the continuous water jet (CWJ) application powered via stagnation pressure. However, it is known that impact pressure is much more effective than static pressure. When the impact pressure is repeated with a high frequency per time unit, the erosive effects of water can be used even at pressures below 100 MPa, which is attractive from the point of view of the low demands of the hydraulic system. Surface modification utilising impact pressure can be achieved by employing the pulsed water jet (PWJ) method. The combination of parameters such as the traverse speed and trajectory pattern can control the number of water clusters impacting the material surface. So far, the field of application of PWJ for surface treatment has mostly been investigated water atmospheric conditions. This article focuses on the possibility of the surface modification of AISI 304L stainless steel using the PWJ method under submerged conditions. The results are compared to those obtained under atmospheric conditions. The reference samples were treated by the same technological conditions using a continuous water jet (CWJ). The affected surfaces were characterised using areal surface roughness parameters Sa, Sz, Sp, and Sv, and the surface topography and mechanism of erosion wear were evaluated by scanning electron microscopy. A significant increase in all roughness parameters was confirmed using the PWJ compared to the CWJ method (both in atmospheric and submerged conditions), which confirms the importance of using impact pressure. The surface treatment by PWJ under submerged conditions resulted in a decrease of the surface roughness parameter Sa by approximately 97% compared to atmospheric conditions at a traverse speed of 2 mm/s for perpendicular interleaved trajectory, nevertheless, the homogeneity of treatment over a larger area was improved.

РОЗРОБКА І ДОСЛІДЖЕННЯ БАГАТОПОЗИЦІЙНОГО ГІДРОАПАРАТУ ТЕХНОЛОГІЧНОЇ МАШИНИ

According to the analysis of the designs of technological machines that have several executive mechanisms that work sequentially according to the technological diagrams and receive movements from the electric drive through chains of mechanical transmission mechanisms consisting of a set of kinematically connected friction pairs and parts, complicated in the design and its production, have reduced reliability in operation. The authors propose a developed hydraulic system for distributing motion to the working mechanisms of the technological machine, which consists of an original design of a multi-position, multi-line hydraulic apparatus, which can ensure the distribution of motion to several hydro motors of the working mechanisms of the technological machine in accordance with the cyclogram of its operation and replace the chains of mechanical transmission mechanisms and parts. The originality of the design of the multi-position, multi-line, single-spool hydraulic device is that it combines the properties of a spool- and valve-type hydraulic distributor, and the spool itself has a complex sectional cylindrical shape with cut sectors and makes a rotary, not reverse translational movement. The developed hydraulic device can perform both distribution and control functions and can replace controlled automatic devices. A math model for calculating the volume of the working cavities of the hydraulic device (hydraulic distributor) was developed. In order to check the operability of the hydraulic apparatus of the new design, its parametric modeling in the SolidWorks system and a cycle of experimental studies using the FloWorks module were carried out. The results of the distribution of liquid in the hydraulic apparatus for individual cavities connected to the hydraulic lines of the hydraulic motors of the working mechanisms of the technological machine were obtained. The principle of designing a new hydraulic device can be used to distribute liquid in technological machines with different cycles of mechanism interaction.

Auxiliary variable-based output feedback control for hydraulic servo systems with desired compensation approach

Auxiliary variable-based output feedback control for hydraulic servo systems with desired compensation approach