Hydraulic Characteristics Research Articles

Design and Test of Hydraulic Driving System for Undercarriage of Paddy Field Weeder

In response to challenges such as inadequate driving stability and power in traditional weeding machinery, we designed and investigated a hydraulic chassis tailored for paddy field operations. Utilizing SolidWorks and RecurDyn V9R4 software, we obtained linear driving and steering curves to model and simulate the dynamics of the mower chassis. Through the AMESim software, we further modeled and simulated the hydraulic chassis system, focusing on the hydraulic characteristics of the components relevant to its operation. Subsequently, we developed a hydraulic-driven paddy weeder and conducted tests to evaluate the linear deviation and paddy slip rates. Our findings indicate that the designed hydraulic weeder chassis exhibits commendable dynamic performance and driving stability, with the actual average deviation and paddy slip rates measured at 2.61% and 3.59%, respectively. These results underscore the efficacy of our approach in addressing the challenges inherent in traditional weeding machinery and highlight the potential of hydraulic systems in enhancing agricultural operations.

Research on the hydraulic support face guard mechanism and coupling characteristic of rib spalling in large mining heights

In view of the problem of poor coupling adaptability and easy rib spalling of coal wall in large mining height comprehensive mining, based on the effective inhibition effect of face guard mechanism on coal wall spalling, the structural characteristics and bearing capacity of different structural forms of the face guard mechanism are compared and analyzed. According to the surrounding rock adaptability of the face guard mechanism, established a numerical analysis model for rigid-flexible coupling of the face guard mechanism under different spalling forms. In order to accurately simulate the stress state of the protective mechanism, a variable stiffness spring damping system is used to replace the hydraulic cylinder. The load-bearing performance and response characteristics of the face guard mechanism under rib spalling coupling conditions were analyzed by applying uniform normal load and impact load to the face guard. The findings indicated that, the integral-type face guard mechanism has a better effect on suppressing rib spalling. When the face guard mechanism bears the static load of the coal wall, the entire response process of the face guard jack can be divided into three stages: initial support, increasing resistance bearing, constant resistance bearing; both the impact load position and the coupling state of the rib spalling will affect the characteristics of force transmission at the face guard mechanism’s hinge point, the hinge point between the extensible canopy and the primary face guard is most sensitive to biased load. The research results can provide reference for optimizing the face guard mechanism of large mining height hydraulic support and improving the reliability of coal wall support.

Numerical Study of the Thermal and Hydraulic Characteristics of Plate-Fin Heat Sinks

One of the main trends in the development of the modern electronics industry is the miniaturization of electronic devices and components. Miniature electronic devices require compact cooling systems that can dissipate large amounts of heat in a small space. Researchers are exploring ways to improve the design of the heat sink of the cooling system in such a way that it increases the heat flow while at the same time reducing the size of the heat sink. Researchers have previously proposed different designs for heat sinks with altered fin shapes, perforations, and configurations. However, this approach to optimizing the design of the heat sink results in an increase in the labor intensity of its production. Our goal is to optimize the heat sink design to reduce its size, reduce metal consumption, and increase heat flow. This goal is achieved by changing the number of fins and the distance between them. In this case, there is no significant difference in the geometry of a conventional plate-fin heat sink, and a low labor intensity of production is ensured. A numerical investigation of heat flow and pressure drop in models of plate-fin heat sinks of various sizes and metal volumes was conducted using the ANSYS Fluent software package (v. 19.2) and computational fluid dynamics employing the control volume method. We used the SST k-ω turbulence model for the calculations. The research results showed that by changing the number of fins and the distance between them, it is possible to increase the heat flow from the heat sink to 24.44%, reduce its metal consumption to 6.95%, and reduce its size to 30%. The results of this study may be useful to manufacturers of cooling systems who seek to achieve a balance between the compactness of the heat sink and its ability to remove large amounts of heat.

Effect analysis of oxide layer on thermal hydraulic characteristics of LBE cooled reactor

For Lead-Bismuth Eutectic (LBE) alloy cooled reactor, oxidation corrosion is very important and would affect the thermal hydraulic characteristics of the reactor. In this paper, based on LETHAC code developed by Xi’an Jiaotong University (XJTU) for system level thermal hydraulic analysis LBE reactor, a simulation module for oxidation corrosion is developed and added. The influence of oxidation layer on the heat transfer characteristics of the reactor is conducted. Based on LESMOR reactor designed by XJTU, a simulation calculation is carried out under the long-term operation conditions of the reactor considering the growth of oxidation layer. The distribution of the oxide layer in the reactor, the change of temperature appreciation caused by the oxide layer over time and the distribution in the reactor are obtained. The presence of oxide layer will affect the fluid temperature and wall temperature of reactor. The longer the run time, the greater the impact. This paper could provide solid analysis methodology reference for the design of LBE reactor.

Hydraulic Jump Characteristics Downstream of a Compound Weir consisting of Two Rectangles with a below Semicircular Gate

Weirs are often used in laboratories, industries, and irrigation channels to measure discharge. The discharge capacity of a structure is vital for its safety and plays an important role in the combined gate-weir flow, which is a complicated phenomenon in hydropower. This study carried out experiments on a combined hydraulic structure, which included a compound sharp-crested weir made up of two rectangles along with an inverted semicircular sharp gate. Installed on a straight channel, this structure served as a control instrument. The study aimed to investigate the downstream hydraulic jump characteristics of this combined structure, specifically, the sequent depth ratio (y2/y1), the hydraulic jump height ratio (Hj/y1), the energy loss ratio through the jump (EL/Eu), and the jump length ratio (Lj/y1). The width of the upper rectangle on the weir was set at 20 cm. The width of the lower rectangle (W2) was set at 5, 7, and 9 cm, while its depths (z) were fixed at 6, 9, and 11 cm. The gate's diameters varied between 8, 12, and 15 cm. These measurements were alternated with varying initial Froude numbers (Fn1) ranging between 1.32 and 1.5. The results showed that the dimensions of both the weir and the gate influenced the hydraulic jump characteristics. Empirical formulas were developed to predict y2/y1, Hj/y1, EL/Eu, and Lj/y1 based on the differing dimensions of the combined structure. The findings and analysis of this study are limited to the range of data that were tested.

Numerical investigation on unstable oscillation of oxygen jet condensation in cryogenic liquid rocket

Oxygen jet condensation always occurs with intense unstable oscillation in the cryogenic delivery pipe of a space launch vehicle. This phenomenon threatens the safety of the propulsion pipeline. It is essential to explore the transient physical features of oxygen jet condensation precisely, including the spectrum of pressure oscillation. Aiming at a deeper understanding of the thermal hydraulic characteristic of oxygen jet condensation, abundant simulations are carried out using a modified phase change method. In this model, the height function method is introduced to capture the interfacial curvature to reveal the mechanism of periodic fluctuation. The simulation proves that three typical flow patterns are found at variant operating conditions in oxygen jet condensation: chugging, oscillation, and swinging. The condensation regime diagram is summarized according to the flow pattern distribution. The chugging flow, along with the phenomenon of liquid oxygen sucked-back flow, shows the most intense pressure oscillation with a maximum amplitude of 133 kPa. In the oscillation flow, the oxygen vapor plume shrinks periodically with a low frequency of about 10 Hz. The swinging flow is a stable flow pattern with a slight pulsation of oxygen vapor plume wake. Its amplitude of pressure oscillation is approximately 1–3 kPa. The influence of liquid oxygen mass flow rate and subcooling on the unstable characteristic is also obtained. These findings offer ample theoretical direction for the development of the space launch vehicle.

Evaluating the effects of soil grain roughness and rill cross‐section shape on flow resistance

AbstractThe knowledge of the hydraulic characteristics of rill flows is needed to improve the understanding and the accurate modelling of upland erosion processes. Flume investigations are developed to schematize conditions useful to analyze the influence of a unique variable significant for modelling rill hydraulics, while field investigations are used to simulate morphological and hydraulic conditions of natural cases. The main aim of this investigation is to compare flow resistance measurements carried out using a rectangular rill channel (flume data) and manually generated and naturally shaped rills (plot data) for the same soils and hydraulic conditions. The two data sets allowed for establishing how the soil grain roughness and rill cross‐section shape affect flow resistance using a theoretical equation deduced by applying dimensional analysis and self‐similarity theory. The analysis developed for a fixed‐bed channel with a rectangular cross‐section demonstrated that the influence of different soil roughness on the Darcy‐Weisbach friction factor is approximately equal to ±1%, while for a rill with an irregular cross‐section the same effect is almost equal to ±2%. Therefore, for an open‐channel flow on a fixed bed, the effect of the grain size roughness on the friction factor is limited. For each examined soil, the investigation also demonstrated that the rill cross‐section shape leads to a variability of the friction factor from −20% to +30%. This result highlights that, for a fixed‐bed channel, the effect of the cross‐section shape on the Darcy‐Weisbach friction factor is much greater than that due to the soil grain size roughness. The main implication of this work is that the results deduced by laboratory measurements with regular cross‐sections, thus neglecting a complex geometry, can be affected by relevant discrepancies from those obtained by the field measurements, which better simulate natural conditions.

The hydraulic characteristics of a subsurface flow stone biofilter for treating polluted runoff from an informal settlement

ABSTRACT Polluted runoff from informal settlements in developing countries poses a growing challenge due to the elevated and variable nature of contaminants, particularly nutrients and pathogens, introduced to the environment. Cost-effective and scalable treatment systems with the ability to reduce nutrient and other pollutant concentrations in contaminated runoff are desirable. Biofilters are passive water treatment systems that have the potential to achieve this. The Franschhoek Water Hub, a research site for nature-based solutions, features six large biofiltration cells designed to remediate runoff from an informal settlement. Due to their large size, understanding hydraulic behaviour and validating the design proves challenging. To address this, a scaled-down version of the Water Hub's biofilters was constructed to inform design criteria for purpose-built filters. The pilot-scale subsurface flow biofilter, filled with 8–11 mm aggregate stone, had an available volume of 225 L. Pulse tracer studies conducted at various flow rates demonstrated that the system approximated plug flow behaviour. Lower flow rates resulted in deeper tracer infiltration, which is crucial for maximising the distribution of nutrients within the filter bed. This research contributes to the effective design and operation of biofiltration systems, which hold promise for addressing surface water contamination issues in resource-constrained regions.

Experimental and simulation analysis of flow patterns and energy dissipation through sluice gates in a U-shaped channel

ABSTRACT The vertical U-shaped gate holds significant potential for widespread application in flow control within U-shaped channels, as it eliminates the necessity for constructing auxiliary hydraulic structures. The boundary conditions associated with the U-shaped gate are complex, offering distinctive hydraulic features. In this study, the hydraulic characteristics of a vertical U-shaped gate have been investigated by model test and numerical simulation on a U-shaped channel under different flow rates, and the hydraulic evolution process was analyzed. The results show that the minimum relative error of discharges is 0.4%, so the numerical simulation can accurately describe the hydraulic performance of the vertical U-shaped gate. The flow generates a contracted cross-section and presents rhomboid water waves with a ‘hump-like’ convex structure after passing the U-shaped gate, accompanied by large kinetic energy dissipation. The gate opening exerts notable influence on the free surface width. The width of the first contraction section increased by 53.88% as the gate opening ranged from 2.5 to 5.5 cm with a flow rate of 8.24 L/s. The power function relationship of upstream flow Froude number, the width of free surface and energy loss is established. The results are helpful for engineering designing and operation management of a U-shaped gate.

Hydrogeological Assessment of the Aquifers in Shwan Sub-Basin, Kirkuk, Iraq

Groundwater is considered one of the main sources of providing water for agricultural, domestic, and industrial activities within the Kirkuk province. The current article aims to assess the groundwater impound and estimate the hydraulic properties of the main aquifers within the Shwan sub-basin. Pumping test was conducted in 6 water wells with the aid of the principal observation wells drilled in the Bai-Hassan formation and Quaternary deposit. Based on the sketches of the drilling wells and according to the results of the hydraulic characteristics the aquifer types lie under the confined to semi-confined conditions. The saturation thickness varies between 35–82 m. The values of hydraulic conductivity ranged between 12–28 m/d the Transitivity is in the range of 570 m2/d–1032 m2/day, and the storage coefficient ranged between 3 x 10-4 – 9 x 10-4. The flow net map was created by measuring the depths of the groundwater from 55 wells drilled inside the area of interest. The depths to the water table range from 7.5 –108 m below the ground surface and the static water level varies from 235–750 m a.s.l. The groundwater flow map shows that the water in the area heads mainly from the eastern towards the western direction, then drains to the Lesser Zab River.

Thermal and hydraulic characteristics analysis of horizontal lead-bismuth reactor assembly based on sub-channel analysis code

In this paper, the self-developed subchannel analysis program SACOS-PB was used to analyze the thermal hydraulic characteristics of 127 rods in horizontal lead-bismuth reactor under steady state and typical ocean transient conditions. The results of the steady-state analysis showed that the coolant flow and temperature of the vertical assembly were symmetrically distributed, the coolant flow of the horizontal assembly gradually increased along the gravity direction, the temperature rose first and then fell, and the peak coolant temperature of the cross-sectional channel was about 365 °C. Three typical ocean transient operating conditions, inclined, undulating and swing, were also carried out. The results showed that the maximum temperature of the coolant at the exit of the assembly increased with the increase of the transverse heeling angle and the decrease of the trim angle after the incline motion changes the gravity component. Under the undulating and swing conditions, the coolant hydrothermal parameters fluctuated periodically, and the parameter fluctuation period is 10s in line with the oceanic conditions. In the above transient conditions, the peak coolant temperature at the assembly outlet increases and exceeds 365 °C. Compared with the pitching motion on the Y-axis, the rolling and tumbling motion on the X-axis had a significant effect on the coolant flow rate and temperature distribution. The calculation results can provide support for the analysis study of the safety characteristics of lead-bismuth power units under marine conditions.

Determination of the diameter variation peculiarities along the path of distribution drainage pipe-line

This article presents a methodology for calculating the hydraulic characteristics and structural parameters of variable (decreasing) cross-sectional distribution pressure drainage pipelines. The approach is based on analyzing a system of differential equations describing fluid flow with a variable flow rate in the investigated pipes. The study explores the most general case of distributor operation, considering a horizontal groundwater level above the pipeline. The analysis of the original equations includes a scenario where a constant average fluid flow rate is maintained along the length of the pressure channel. The velocity magnitude is influenced by the granulometric features of the surrounding soil and the filtration characteristics of the pipeline's side walls material. The investigation employs the concept of a conditional distribution infinitely long pipeline or a pipeline with limited length and infinite permeability of the side walls surface. This allows assuming a pressure close to zero at the pipeline's final cross-section, which minimally impacts the obtained results. The analysis is presented in a dimensionless form, and the resulting computational formulas are both simple and convenient. The article includes corresponding graphs to illustrate the presented dependencies.

Deformation and Strength of Unsaturated Loess—Hydraulic Coupling Effects under Loads

The volumetric change in unsaturated loess during loading causes serious damage to the foundation and structure, accompanied by changes in hydraulic conditions. Therefore, quantifying the change in the load effect of loess under hydraulic coupling is of great significance for revealing the mechanism of hydraulic interaction. This study conducts isotropic compression and undrained shear tests on unsaturated compacted loess, simultaneously introducing the strength parameter η to enhance the Glasgow coupled model (GCM). The objective is to elucidate the hydraulic and mechanical coupling mechanism, where saturation increases under mechanical effects lead to strength degradation. The results show that saturation increases under mechanical effects improve the compressibility of the sample, and saturation has a direct impact on the stress–strain relationship. The increase in water content and confining pressure increases the trend of the critical state stress ratio M decreasing, and the strain softening trend increases. The compression of volume during shear tests increases the saturation, changes the hydraulic characteristics of loess, and affects the deformation and strength of loess. The modified GCM improves the applicability and prediction accuracy of unsaturated loess under the same initial state. The research results are of great significance for revealing the hydraulic and mechanical behavior of loess.

Hydraulic characterization of Pwales aquifer in Malta Island preparatory for planning managed aquifer recharge (MAR) pilot plant

Whitin the aim to reduce the water demand by increasing water use efficiency and providing alternative water resources, and mainly to meet the demand of good quality irrigation water for agriculture, the Energy and Water Agency of Malta is planning to develop a Managed Aquifer Recharge pilot plant in Pwales Valley to improve the quantitative and qualitative status of the groundwater body. For this reason a detailed hydraulic characterization of the valley was carried out. Specifically, hydraulic properties of the rocks that constitute strata atop of the Pwales aquifer were determined by means of both laboratory measurements on samples and field test carried out in the studied area. The water retention and hydraulic conductivity functions, which relate the matric potential, ψ, and hydraulic conductivity, K, to the water content, θ, respectively, were measured using three experimental methods because each of them allows to obtain data points in a specific wet range. The water retention and hydraulic conductivity functions were measured on samples extracted from blocks of Upper Coralline Limestone formation, that hosts the aquifer, collected in three different quarries: Ghian Tuffieha, Mellieha and San Martin areas. The measured water retention and hydraulic conductivity data were fitted with LABROS SoilView Analysis software that allows to describe the functions and obtain the parameters which are crucial for modelling the water flow and transport processes in the critical zone. In addition, large ring infiltrometer test was carried out to determine the field saturated hydraulic conductivity, Kfs, and the average infiltration rate. Knowledge of the hydraulic characteristics of the Upper Coralline Limestone, completely missing in the scientific literature, allows developing a local groundwater-flow numerical model in order to better describe and understand how the water flows from the soil to the groundwater of the valley and visualize different environmental scenarios such as the potential effects of Managed Aquifer Recharge plant in the Pwales Coastal Groundwater Body.

Results of the Studies of the Pump and Network Characteristics of the Plant for the Production of Grain Molasses

The article describes the results of an experimental and theoretical estimation of the pressure characteristics of the network of the plant for the production of grain molasses with a centrifugal pump 1SM 65-50-160/2-m. Measuring equipment and conditions for obtaining hydraulic characteristics are presented. For accelerated heating of water to 30C, a cavitator in the form of a cone with petals is proposed. The operating point of the pump has been defined.

Physics-Informed Graph Neural Networks for Water Distribution Systems

Water distribution systems (WDS) are an integral part of critical infrastructure which is pivotal to urban development. As 70% of the world's population will likely live in urban environments in 2050, efficient simulation and planning tools for WDS play a crucial role in reaching UN's sustainable developmental goal (SDG) 6 - "Clean water and sanitation for all". In this realm, we propose a novel and efficient machine learning emulator, more precisely, a physics-informed deep learning (DL) model, for hydraulic state estimation in WDS. Using a recursive approach, our model only needs a few graph convolutional neural network (GCN) layers and employs an innovative algorithm based on message passing. Unlike conventional machine learning tasks, the model uses hydraulic principles to infer two additional hydraulic state features in the process of reconstructing the available ground truth feature in an unsupervised manner. To the best of our knowledge, this is the first DL approach to emulate the popular hydraulic simulator EPANET, utilizing no additional information. Like most DL models and unlike the hydraulic simulator, our model demonstrates vastly faster emulation times that do not increase drastically with the size of the WDS. Moreover, we achieve high accuracy on the ground truth and very similar results compared to the hydraulic simulator as demonstrated through experiments on five real-world WDS datasets.

Research on thermal hydraulic characteristics of reflooding process based on core multi-channel model in system analysis code

There are four main stages in PWR Loss of Coolant Accident (LOCA): blowdown, re-irrigation, re-flooding and long-term cooling. The re-flooding stage is a critical phase to avoid core meltdown and achieve long-term cooling. RBHT reflooding experiment was simulated with the RELAP5 and COSINE program respectively.Thermal-hydraulic characteristics in re-flooding phase were analyzed using multi-channel model. Quench time is mainly influenced by system pressure and coolant subcooling. Later quench will result in a higher cladding temperature. Comparatively, the peak cladding temperature is less affected by the power of the heating rod and the re-flooding rate, which fluctuates within 7 %. The higher re-flooding rate allows quenching to occur as fast as possible and improves cooling efficiency. However, higher coolant sub-cooling and re-flooding rates may cause greater thermal stresses on the core and endanger core integrity. Based on the analysis of the re-flooding rate on the peak cladding temperature and quench time, the optimal re-flooding rate interval of 0.099–0.105 m/s was obtained.

Numerical analysis of hydraulic characteristics of resting pool in improved vertical slot fishway

When fish swim upstream in the long-distance fishways, fatigue may occur, thereby affecting their passage efficiency and passage time. Therefore, constructing suitable resting pools within the fishway is essential. In this study, a diversion pile was introduced into the resting pool of the vertical solt fishway while altering its installation position. A three-dimensional re-normalization group k– ε turbulent mathematical model was then employed to analyze how the diversion pile with distinct positions affects the hydraulic characteristics in the resting pool under different slope conditions. The results show that with the diversion pile at the two-thirds position of the partition wall’s sidewall in the resting pool, the mainstream is effectively regulated to the central position, accompanied by a small degree of meandering. Under such an arrangement, although the diversion pile has an impact on the turbulent kinetic energy in the resting pool across various slope conditions, the influence is insignificant. Therefore, it is recommended to install the diversion pile at the two-thirds position of the partition wall’s sidewall in the resting pool, which can adjust the hydraulic characteristics of the resting pool and provide a large range of low-velocity areas for fish to rest, thereby facilitating the passage efficiency.

In Situ Rainwater Harvesting System Slows Forest Decline through Increasing Soil Water Content, Fine-Root Traits, and Plant Hydraulic Conductivity

Large-scale vegetation restoration campaigns have been implemented on the Chinese Loess Plateau, which have resulted in higher soil moisture deficits in this region. This, in turn, has hampered the healthy growth of planted trees, leading to a decline and, in severe cases, mortality of trees. Therefore, the rational regulation and utilization of rainwater, the primary water source in this region, may alleviate drought stress, ensuring the sustainability of the ecosystem. In this study, we investigated the impact of in situ rainwater collection and infiltration systems (IRCISs) on soil water, fine-root distribution, xylem vascular, and hydraulic conductivity characteristics in declining Robinia pseudoacacia forests. The results demonstrated that the application of an IRCIS can effectively increase plant available moisture content (0–5.0 m) of declining Robinia pseudoacacia forests. In particular, IRCIS treatment significantly increased xylem conduit diameter and plant hydraulic conductivity while substantially reducing the percentage loss of hydraulic conductivity in both roots and branches. Furthermore, IRCIS treatment significantly reduced the root biomass and distribution depth of Robinia pseudoacacia during both wet and dry years. This implies that IRCISs are beneficial for plant growth and survival. The findings of this study are significant for devising strategic methodologies for the planning and management of rainwater resources.

Research on the Development of a Dispatching Scheme for Maneuvering the Filling and Drawdown Water Intake Gates of the Kaparas Reservoir

Purpose: The research aims to explore the laboratory hydraulic characteristics of the "Kapa-ras" water intake facility, specifically focusing on devising a control strategy for maneuvering gates amidst fluctuating flow rates and water levels in both the upstream and downstream ar-eas. Methods: Laboratory experiments were conducted to assess the performance of the water in-take facility under different gate opening schemes. These experiments included determining the capacity of the "Kaparas" reservoir intake for various gate configurations and establishing the discharge coefficient dependencies on the relative gate openings. Additionally, a series of experiments were conducted to ascertain the maximum allowable downstream depth without causing erosion to the attachment bottom, considering all potential gate opening scenarios. Results and conclusion: The main results yielded insights into the hydraulic behavior of the "Kaparas" water intake facility, enabling the determination of optimal gate control strategies for maintaining efficient water intake operations. Results indicated varying capacities for the reservoir intake under different gate configurations, and the dependence of discharge coeffi-cient on gate opening relative to the flow rates. Moreover, permissible downstream depths were identified to prevent erosion, ensuring the structural integrity of the attachment bottom. Consequently, these findings contribute to the effective management of water resources at the "Kaparas" facility. Research implications: The research outcomes provide valuable insights for enhancing the operational efficiency and sustainability of water intake facilities similar to "Kaparas." The findings can inform decision-making processes regarding gate control strategies and down-stream depth management, ultimately optimizing water resource utilization and mitigating po-tential environmental risks. Originality/value: This study contributes novel empirical data and analytical insights into the hydraulic behavior of water intake facilities, particularly in the context of gate maneuvering and downstream depth management. The research fills a gap in understanding the operational dynamics of such facilities and offers practical implications for hydroelectric complex man-agement, facilitating informed decision-making and resource optimization.