Hydraulic Power Research Articles

Design and Research of Dual-Mode Power Generation Device Based on Improved Oscillating Buoy

In response to the national “dual-carbon” strategic goals, a dual-mode ocean energy generation device was researched. First, improvements were made to the power generation system and mechanical structure of an oscillating buoy with a radius of 2.5 m, designing a power generation device that utilizes both wave energy and tidal energy. Subsequently, wave generation was carried out using the Realizable k-ε turbulence model, and the buoy’s strength was analyzed using the Ansys Fluent simulation platform with finite element analysis, with simulation results indicating a rational design. Then, the Froude–Krylov hypothesis method and the oscillating buoy body decomposition method were used to calculate the combined force in the vertical direction of the buoy, and combined with other forces, the maximum wave force on the buoy was determined. It was verified that the buoyancy of the buoy met the requirements of the hydraulic system. Finally, the hydraulic power generation system model was simulated and analyzed using AMEsim, yielding a power generation of 55.2284 kW. Using a formula, the maximum power generation of a single buoy was calculated to be approximately 15.5 kW, and the ideal maximum power generation of the entire device was able to reach 101.7284 kW.

Analysis of Indicators of the Electrical Power Production Enterprises’ Pollution and Harm Risk Degree in Terms of the Paris Agreement

Abstract In the current decade, electricity consumption will increase by more than 16%. The main resources for electricity generation are oil – 2.53%; gas – 22.9%; coal – 35.98%; nuclear industry – 9.84%; hydraulic power regeneration – 15.01%; renewable sources – 12.85%; other – 0.89%. This causes global warming of the planet due to greenhouse gases increased emissions into the atmosphere. A resource capable to cover the thermal energy field’s balance is the nuclear energy. To compare the resources’ polluting capacity, it is necessary to introduce a general indicator that takes into account their properties. This study proposes an integrated approach based on the formation of groups of indicators reflecting greenhouse gas emissions; power consumption; economic activity, air quality, etc. For comparison needs, all indicators are normalized in dimensionless form and compiled with reference to their specific weight. Calculations of the pollution index for fossil resources and nuclear energy, carried out using this algorithm proved that the nuclear power, with a careful consideration of all possible polluting radionuclides (11 components), exceeds this indicator for gas by 22%, but is lower than ciphers for coal and oil by 36 and 26%, respectively. For two latters only 3 specific components being taken into account. Therefore, it seems advisable to use the considered complex indicator of environmental pollution to assess the resource safety level for electricity generation.

Calculations of Performance Characteristics of Submerged Cargo Pumps with Hydraulic Drive and Constant Torque Controllers, Taking into Account the Energy Efficiency of the Drive Motor

Submerged cargo pumps installed on board tankers are one of the most important components of their cargo system. As they are installed directly in the cargo tanks, they are usually equipped with a hydraulic drive whose power and capacity are controlled by constant-torque controllers. These have a significant impact on the technical and performance characteristics of the cargo pumps. This paper presents a methodology for calculating the performance characteristics of submerged cargo pumps, taking into account the energy efficiency of their hydraulic drive motors. Due to their number and power, the cargo pumps are powered from the ship’s hydraulic central loading system. This paper describes the main parts of the hydraulic power system structure and the functions of the constant torque controller of the STC type. A mathematical model has been developed to use the basic characteristics of submerged cargo pumps made for the base cargo (water) sent by the pump manufacturer for the case of handling liquid cargo with different parameters. The model considers the characteristics of the hydraulic drive, including a Bosch Rexroth A2FM type hydraulic drive motor and a constant torque controller. The results of simulation calculations of the performance characteristics of an example cargo pump are presented and compared with measurements of the characteristics of this pump on a product tanker. The mathematical model presented in this paper is of utilitarian value, enabling calculations to be carried out without the need for time-consuming CFD numerical methods, making it useful for port and fuel terminal logistics services, ship crews and services managing the operation of product tanker fleets.

Unsteady flow rate in transient, incompressible pipe flow

AbstractKnowledge regarding current flow rates through pipes and other components is crucial for most hydraulic systems. The hydraulic power can be computed in combination with the pressure, which may be used in many applications, such as predictive maintenance. Most flow rate sensors used in the field of fluid power operate invasively. Therefore, the measurement process itself alters the flow rate. Furthermore, most sensors operate accurately for stationary flow but produce inaccurate measurements for transient flow. A well‐known method of determining the flow rate is to measure the pressure difference between two points along a pipeline and calculate the flow rate based on the law of Hagen and Poiseuille. However, since the relation mentioned above only applies to laminar, steady, and incompressible flow, its usefulness for transient flows is limited. This paper derives a system equation based on the fundamental laws of fluid mechanics, which describe transient, incompressible pipe flow. As a result, the fundamental equations are solved in the Laplace domain and subsequently transformed back into the time domain. The four‐pole theorem relates the pressure difference and the volumetric flow rate. The analytical solution consists of a convolution integral containing a weighting function and the pressure difference. Compared to a simulation, the novel equation displays high accuracy for transient and stationary incompressible pipe flow. This equation paves the way for a soft sensor, which allows the noninvasive measurement of arbitrary volumetric flow rates within pipes.

Design and matching control strategy of electro-hydraulic load-sensitive hydraulic power unit for legged robots

A hydraulic power unit is the core energy source of hydraulic legged robots, ensuring the robot's maneuverability and carrying capacity in complex terrains. However, its pressure and flow output are usually set to a fixed level under all working conditions, which leads to mismatched pressure and flow requirements of hydraulic drive units. This mismatch reduces the stability and control accuracy of the hydraulic drive units and results in significant energy waste. To address these issues, this paper proposes an electro-hydraulic load-sensitive hydraulic power unit and a matching control strategy to better align outputs with requirements, thereby enhancing energy efficiency. Firstly, with the variable speed servo motor driving axial piston pump as the core, the closed system working principle of an electro-hydraulic load-sensitive hydraulic power unit is proposed, and the mathematical model of key components exhibiting strong nonlinearity and time-varying parameters is derived. After that, a matching control strategy based on flow feedforward and pressure difference compensation feedback is proposed. Finally, simulations and experiments are conducted to verify the feasibility of the unit and its matching control strategy. This paper provides a new solution for the design and control of hydraulic power units, laying the groundwork for achieving high-performance hydraulic systems.

An experimental study to evaluate the performance of variable-width channel cold plates for cooling rectangular Li-ion batteries

The limited cooling capacity of cold plates employing conventional channel designs represents a key obstacle in thermal management systems. The persistent growth of the thermal boundary layer and the uneven distribution of flow across the channels are the principal challenges encountered in this context. To overcome these challenges, this study aims to analyse a modified cold plate of obstructed variable-width channels that can improve the hydrothermal performance and temperature uniformity. Different shapes of pin fins and grooves with variable sizes that match the width of the variable-width channels are proposed. Specifically, four types of pin fins–grooves were used: ellipse, drop, rhombus and trapezoid. The traditional cold plate served as a basis for evaluating the performance of new designs of cold plates. In addition to the traditional cold plate, the four proposed designs of cold plates were manufactured from copper. Experiments were conducted with water as a working fluid under a laminar flow for a flow rate range of 0.004–0.04 kg/s and a discharge C-rate range of 1C–2C. Results indicated that the use of variable-width channels with all shapes of fins–grooves effectively contributed to improving the heat dissipation of the cold plate, accompanied with an increase in hydraulic pumping power. At the highest flow rate, the best improvement percentage in the Nusselt number of 82.5% was achieved when trapezoidal pin fins–grooves were used; by contrast, the lowest pumping power increasing percentage of 33.2% was obtained when elliptical pin fins–grooves were adopted. The best hydraulic/thermal performance was achieved when trapezoidal pin fins were utilised, with the highest figure of merit of 1.685.

Problems of testing and operation of hydraulic power transfer units

The purpose and principles of operation of a civil aircraft emergency system including a power transfer unit are considered. Problems and trends of the development of piston hydraulic machines in aircraft construction are analyzed. The parameters of power transfer units used on 12 types of passenger airplanes are analyzed. The scenarios of failure of power transmission units are considered. The main directions of solving the problems of operation, as well as the requirements to design and testing are outlined.

Active Disturbance Rejection Control of Engine Speed in Series Hydraulic Hybrid Power System

Abstract: In this paper, a novel series hydraulic hybrid powertrain is proposed for a three-axis all-terrain vehicle. The engine drives two variable displacement pumps responsible for driving and steering, respectively. A variable displacement motor is connected to the ring gear of the planetary coupling mechanism to drive the vehicle and a fixed-displacement motor is connected to the sun gear to steer the vehicle. The active disturbance rejection control with feedforward control is employed to control the engine speed. The engine speed is controlled in a close-looped manner by adjusting the engine throttle. The controller parameters are decided by analyzing the influence of each parameter on the controller performance by means of the control variable method. The simulation results indicate that the proposed control strategy enables the vehicle to obtain better engine speed following and anti-disturbance performance. An all-terrain prototype is established and field tests are carried out to verify the effectiveness of the design and control strategy of the series hydraulic hybrid powertrain for the all-terrain vehicle.

Wave-to-wire modelling and hydraulic PTO optimization of a dense point absorber WEC array

We investigate the hydrodynamic interactions and power extraction efficiency of a dense array of Point Absorber (PA) Wave Energy Converters (WECs) clustered around the fixed pillar of a wind turbine –the Ocean Grazer device– with a standard hydraulic Power Take-Off (PTO) system. Using potential flow theory, a detailed wave-to-wire model is developed in WEC-Sim with four distinct hydraulic PTO designs: i) Multi PTO-with individual hydraulic PTO systems for each buoy, ii) Shared PTO V1-with a unified PTO system for the entire array, iii) Shared PTO V2-with the accumulator volume split into two segments, and iv) Shared PTO V3-with four strategically distributed segments. Key parameters such as the diameter of the hydraulic pistons, volume and pre-charged pressure of the high-pressure accumulators, hydraulic motor displacement and the speed of the electric generator are optimized with a genetic algorithm and a parametric analysis across various sea states. The results highlight that strategically allocating the accumulators across the floaters of a dense WEC array can yield significantly higher power production and should be considered at the early design stages.

Complementary Analysis and Performance Improvement of a Hydro-Wind Hybrid Power System

Hydropower as a flexible regulation resource is a rare choice to suppress the ever-increasing penetration of wind power in electrical power systems. The complementary characteristics and performance improvement of a hydro–wind hybrid power system based on a mathematical model of the hybrid power system is studied in this paper. This established model takes into account the stochastic variation in wind speeds in the wind power subsystem and the hydraulic–mechanical–electrical coupling characteristics of the hydropower subsystem. The complementary analysis is conducted based on the evaluation variables outputted by the established model, such as the wind power, hydro-regulation power, hydraulic power, and frequency. To make full use of the regulation capability of the hydropower system, the optimization of parameter settings is also carried out to improve complementary performances of the hybrid power system. The results from the complementary analysis show the detailed characteristics of hydro–wind coordinated operation under different types of real wind speeds. Here, 95% of installed hydro-capacity is used to complement the power shortage of the intermittent wind energy under the low wind speed. Alternatively, only around 66% of the installed hydro-capacity can be utilized to cope with the fluctuation in wind power under the medium and high wind speeds before the optimization of parameter settings. The recommended values and change rules of the control, hydraulic, and electrical parameters for the hydropower system are subsequently revealed from the analysis of parameter settings to contribute to a stable and safe hybrid power system. The results show that the optimized parameter can increase the maximal regulating capacity of the hydropower system by nearly 9 MW, approximately a sixth of the total installed hydropower capacity. The method and results obtained in this paper provide theoretical and technical guidance for the safe and economical operation of power stations.

Research on the distribution structure of 2D piston electro-hydraulic pump based on fluid-structure interaction

To address the drawbacks of traditional hydraulic power units, we embedded a 2D piston pump inside the motor rotor, proposing a 2D piston electro-hydraulic pump. The space cam mechanism serves as the primary force-bearing structure during its operation. Excessive wear occurs at the highest point of the space cam when subjected to significant axial forces, which leads to deviations between the motion law of the 2D piston and the theoretical design. Aiming this problem, we conduct research from two perspectives: theoretical analysis and fluid-structure interaction. Firstly, the operational principle of the electro-hydraulic pump is introduced. Then, the contact normal stress of the space cam mechanism is studied, and backflow and chamber pressure overshooting are discussed. Finally, the fluid-structure interaction model of the electro-hydraulic pump is established. Based on the fluid-structure interaction model, the effects of the width and depth angles of the triangular damping groove on the backflow and chamber pressure overshooting are analyzed. The simulation results demonstrate that adding triangular damping grooves can improve the flow field characteristics. With the increase in the width and depth angles, the peak flow of the backflow and chamber pressure overshooting increase, with the depth angle exerting a more pronounced effect.

Hydraulic valve design methodology for hydro turbine control system

The control of the turbine and its equipment in a hydroelectric power plant requires the HPU (hydraulic power unit) to deliver large volumes of working fluid in a short time at specific optimum control parameters. The use of typical proportional flow control valves created by manufacturers of hydraulic components in low-pressure control systems is disadvantageous due to high pressure losses in the control chambers. This paper presents the methodology and test results while designing a hydraulic proportional valve for low pressure and high flow rate operation. CFD (computational fluid dynamics) theory was analyzed and characteristic values were determined. The validation of CFD tests through those on the test bench was carried out, correction factor was determined. A new proprietary solution was developed and a series of simulation studies were carried out to determine the flow characteristics depending on the degree of the opening of the proportional flow control valve.

Design and Testing of a Multi-Cylinder Piezopump for Hydraulic Actuation

Hydraulic actuation systems are widely used in industries such as aerospace, the marine industry, off-highway vehicles, and manufacturing. There has been a shift from the hydraulic distribution of power from a centralized supply to electrical power distribution, to reduce the maintenance requirements and weight and improve the efficiency. However, hydraulic actuators have many advantages, such as power density, durability, and controllability, so the ability to convert electrical to hydraulic power locally to drive an actuator is important. Traditional hydraulic pumps are inefficient and unsuitable for low-power applications, making piezopumps a promising alternative for the conversion of electrical to hydraulic power in the sub-100 W range. Currently, the use of piezopumps is limited by their maximum power (typically a few watts or less) and low flows. This paper details the design, simulation, and testing of a multi-cylinder piezopump designed to push the envelope of the power output. The simulation results demonstrate that pumps with two or three cylinders show increasing benefits in terms of hydraulic and electrical performance due to the reduced flow and current ripple compared to a single-cylinder pump. The experimental results from a two-cylinder pump confirm this, and the effect of the phase relationship between the drive signals is investigated in detail. The experimental pump has fast-acting disc-style reed non-return valves, allowing piezostack drive frequencies of up to 1.4 kHz to be used. Custom power electronics tailored to the pump are developed. These features are critical in demonstrating the potential for multi-cylinder piezopumps to play an important role as a future actuation solution.

Planning of Uwe River PLTMH Jayawijaya Regency Capacity 2 X 750 KW

Indonesia has great potential to develop renewable energy, especially through Micro Hydro Power Plants (MHP) that utilize river flow. The Papua region, including Jayawijaya Regency, has significant water resources potential but has not been optimally utilized to meet local energy needs. This study aims to evaluate the technical feasibility of building an MHP in Uwe River, Jayawijaya Regency, with a capacity of 2 x 750 kW as an effort to increase the electrification ratio in Papua Mountains. The research uses a quantitative approach with field survey methods and primary data collection, such as water discharge measurements and interviews with relevant parties. The data were analyzed using the FJ Mock method for water discharge estimation and hydraulic power calculation to assess the technical feasibility of MHP development. The results showed that Uwe River has a potential hydraulic power of 2063.965 kW with a capacity factor of 88%, which is able to support the operation of two turbines with a capacity of 733.76 kW each. The conclusion of this study shows that the construction of an MHP in Sungai Uwe is technically feasible and has great potential to increase the electrification ratio, support local economic development, and reduce dependence on fossil fuels in remote areas. The implication of these results is the importance of investment and policy support in the development of renewable energy projects in Papua to achieve national electrification targets.

Analysis of the Newest Design of Axial Piston Hydraulic Machines with Reduced Friction Losses and Leaks

Problem. Analysis of modern achievements in the field of volumetric hydraulic drives to improve the technical level of construction and road machines. Goal. Study of the design of the latest foreign development related to the improvement of the technical level of axial-piston volumetric hydraulic machines, in particular pumps and hydraulic motors according to the scheme of Innas floating cylinders. This design, according to the proposal of its inventors, is intended to work as pumps with a flow of up to 7400 l/min or hydraulic motors with a working volume of up to 5000 cm3 at a pressure of up to 50 MPa. Methodology. Analysis of the results of comparative bench tests of the Innas axial piston pump of the latest development and volumetric hydraulic machines of various designs, in particular axial and radial piston, as well as gear ones. Results. According to the results of comparative tests, the new design of the Innas axial-piston pump is significantly ahead of other serial hydraulic machines in terms of efficiency. The total efficiency value of 96 % achieved in the Innas pump shows the promise of such hydraulic machines. Originality. Analysis of the results of experimental studies with the determination of the features of the structures of hydraulic machines in terms of volumetric and hydromechanical power losses. It is concluded that Innas hydraulic motors can be used in trailing volumetric hydraulic drives with hydraulic power amplifiers, for which the characteristic of friction in the displacement mode is the main one from the point of view of the accuracy of the execution of the specified control signals. Practical value. The given materials are useful for specialists in the field of mechanical engineering, in particular, the design of volumetric hydraulic drives for construction and road machines

Numerical investigation of tip clearance designs for oblique-cut fin microchannels

Tip clearance represents a simple design intervention strategy to mitigate the high hydraulic penalties often associated with microchannel heat sinks. This approach has not been widely explored for enhanced microchannel heat sinks, having previously focused only on conventional (uniform) tip clearance design for straight microchannels. In view of this, the present work investigates the performance of an enhanced heat sink, specifically oblique-cut fin microchannels, with tip clearance designs. Two different designs are considered, namely conventional/uniform tip clearance (utc) and a newly conceptualized modulated tip clearance (mtc). Numerical simulations are conducted using ANSYS FLUENT 2022 R1 first for straight microchannels, which are considered the baseline to which oblique-cut fin microchannel designs are compared. The simulations are carried out under laminar flow regime including conjugate heat transfer in a heated solid substrate for flow rates of 250 – 650 mL/min. The results indicate that utc significantly reduces pressure drop though can increase thermal resistance for the oblique channels. The underlying physical mechanisms responsible for this observation are elucidated by examining thermal and flow behaviours in and around oblique cut slots. Based on the flow behaviour in oblique slots with utc, modulated tip clearance (mtc) concept is introduced and investigated. When compared to utc cases, mtc tends to reduce the thermal resistance substantially, though depending upon oblique cut angle and flow rate. However, the Performance Index (PI) shows that utc improves the overall performance in the range of 10–15 % compared to that observed with mtc cases, though the factor of improvement reduces closely to 5 % at 650 mL/min. In addition, the overall performance in terms of heat transfer and hydraulic pumping power further show that utc and mtc design strategies are competitive, and warrant further multi-objective optimization investigations to determine the best design option overall.

Design Optimization of a Point Absorber and Hydraulic Power Take-Off Unit for Wave Energy Converter

Design Optimization of a Point Absorber and Hydraulic Power Take-Off Unit for Wave Energy Converter

Analysis of the principles of working load formation in power drives of construction machines and equipment

The purpose of the proposed article is the analysis of the principles of the formation of the workload on the executive bodies of construction machines and technological equipment, which is due to the need for their improvement in order to improve the energy and technological indicators of technological processes.The methodology is based on search, research and creative approaches. The methods of development analysis, patent search, synthesis of technical solutions, simulation modelling was used. Scientific novelty. The study of various approaches to ensuring the implementation of the working movements of executive bodies of construction machines and mechanized technological equipment, the analysis of technical solutions allowed to substantiate the directions of development of drives of construction machines to ensure the necessary laws of movement of executive elements. The authors proposed constructive solutions for synthetic drives of construction machines and equipment, proposed energy-saving approaches aimed at reducing energy consumption. Research results. The article deals with important issues of analyzing the formation of loads on executive bodies of construction machines and equipment. Synthesized constructive solutions obtained in the course of patent research, analysis of modern technical solutions, rational technical design and expert evaluation are presented. A technical solution is proposed to ensure the implementation of adaptive feed in a hydraulic power drive, which can be used in the modernization of existing drives of construction machines and moving parts of mechanized technological equipment.

Analysis of an evaporator with single horizontal circular micro-tube using FC-72 as working fluid for electronic cooling applications

Flow boiling in micro-channels is one of the most efficient methods for heat rejection in electronics, necessitating proper system design. Numerical simulations are the most suitable tool for this purpose, with most literature focusing on CHF situations, while few studies address conditions bellow it. This paper presents a parametric analysis of an evaporator with a horizontal circular micro-tube, maintaining a fixed outlet quality, using numerical simulation. The simulation employs a one-dimensional steady-state model with FC-72 as the working fluid, considering both subcooled liquid and two-phase lengths, computed using theoretical equations and correlations. The effects of inner tube diameter, heat flux, inlet pressure, and subcooling level on key evaporator design parameters are discussed in detail. Results indicate that to minimize hydraulic pumping power, fluid temperature difference, and inlet temperature are required, the evaporator should operate with the lowest heat flux (50kW∙m-2), the largest inner tube diameter (1.3mm), the highest subcooling level (30K), and the lowest inlet pressure (2bar). Under these conditions, hydraulic pumping power can be reduced by up to 86%. Furthermore, to achieve the minimum fluid temperature difference along the tube (approximately 4.9K) and avoid CHF situation, operation with the lowest subcooling level (5K) is necessary. Finally, the ratio of the heat flux to the critical heat flux, q"/CHF, increases with rising inlet pressure and subcooling level, and/or decreasing inner tube diameter. The minimum q"/CHF ratio of 43.9% was obtained at pin=2bar, q"=50kW∙m-2, D=0.9mm, and ΔTsub=5K. These findings provide insights into optimal design parameters for evaporators in micro-electronics cooling applications.

Modeling the Normal Water-Energy Operating Modes of Hydraulic Power Equipment in Pumped Storage Power Plants Considering Maneuverability Indicators

Modeling the Normal Water-Energy Operating Modes of Hydraulic Power Equipment in Pumped Storage Power Plants Considering Maneuverability Indicators