scholarly journals Transient Phenomena Generated in Emptying Operations in Large-Scale Hydraulic Pipelines

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2313
Author(s):  
Guillermo Romero ◽  
Vicente S. Fuertes-Miquel ◽  
Óscar E. Coronado-Hernández ◽  
Román Ponz-Carcelén ◽  
Francisco Biel-Sanchis
Keyword(s):  
Mathematical Model ◽  
Hydraulic System ◽  
Large Scale ◽  
Hydraulic Systems ◽  
Transient Phenomena ◽  
Pressure Drops ◽  
Pipeline Route ◽  
Air Pockets ◽  
Pressure Changes ◽  
The Mathematical Model

Air pockets generated during emptying operations in pressurized hydraulic systems cause significant pressure drops inside pipes. To avoid these sudden pressure changes, one of the most widely used methods involves the installation of air valves along the pipeline route. These elements allow air exchange between the exterior and the interior of the pipe, which alleviates the pressure drops produced and thus prevents possible breaks or failures in the structure of the installation. This study uses a mathematical model previously validated by the authors in smaller installations to simulate all hydraulic variables involved in emptying processes over time. The purpose of these simulations is the validation of the mathematical model in real large-scale installations, and to do this, the results obtained with the mathematical model are compared with actual measurements made by the partner company. The hydraulic system selected for the study is a pipeline with a nominal diameter of 400 mm and a total length of 1020 m. The results obtained from the mathematical model show great similarity with the experimental measurements, thus validating the model for emptying large pipes.

Simulation Analysis of Rotary Steering Pump-Control Hydraulic System

2013 ◽  
Vol 295-298 ◽  
pp. 1995-2000
Author(s):  
Guang Fu Chen ◽  
Xiao Xian Yao ◽  
Si Bao Li
Keyword(s):  
Mathematical Model ◽  
Comparative Analysis ◽  
Input Signal ◽  
Hydraulic System ◽  
Simulation Analysis ◽  
Harsh Environment ◽  
Hydraulic Systems ◽  
New Form ◽  
The Mathematical Model ◽  
Valve Control

The traditional valve control hydraulic systems have serious challenges in the harsh environment underground. The mathematical model of this new form of "motor - quantitative pump" controll system was established and simulated by using AMESIM software in this paper. According to the results of comparative analysis of the orifice parameters and the way to input signal, related parameters was determined, which can meet the characteristics of the system.

scholarly journals ALGORITHM OF CONTROLLING AN ADAPTIVE HYDRAULIC CIRCUIT FOR MOBILE MACHINES

2021 ◽  
Vol 13 (3) ◽  
pp. 79-86
Author(s):  
Leonid Kozlov ◽  
◽  
Yurii Buriennikov ◽  
Oana Rusu ◽  
Volodymyr Pyliavets ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Hydraulic System ◽  
Hydraulic Systems ◽  
Hydraulic Circuit ◽  
Nonlinear Mathematical Model ◽  
Rosenbrock Method ◽  
Soil Hardness ◽  
Loose Soil ◽  
Feed Value ◽  
The Mathematical Model

Hydraulic systems based on adjustable pumps, proportional electrohydraulic equipment and controllers are used in mobile machines. The authors propose a new scheme of the hydraulic system for mobile machines, which provides the auger drilling operation. A number of studies have shown that a certain ratio should be maintained between the frequency of auger rotation and its feed during operation, where the productivity of soil disruption should not exceed the productivity of transporting loose soil from the drilling zone. Ensuring the required ratio between the speed of the auger rotation and its feed is implemented by a controller that works according to a certain algorithm. A nonlinear mathematical model of the hydraulic system was developed to create the algorithm for controller operation and setting. The equations of the mathematical model are solved in the MATLAB-Simulink environment by the Rosenbrock method. As a result of solving the equations for the mathematical model, the dependences of variables describing the state of the hydraulic system on time are obtained. The values of the controller settings are determined at which the hydraulic system works steadily, the error of flow rate stabilization, the time for pressure adjustment and readjustment does not exceed the allowable values. The algorithm for controlling the auger feed value is formed. This algorithm provides the necessary ratio between the auger feed and speed, as well as reducing the feed rate in the case of soil hardness increases. This creates the conditions for uninterrupted pit drilling at full depth and protection of the hydraulic system from overload.

Pressure Changes Induced by Whole Body Acceleration Shocks

1991 ◽  
Vol 113 (1) ◽  
pp. 27-29 ◽  
Author(s):  
E. Belardinelli ◽  
M. Ursino ◽  
G. Fabbri ◽  
A. Cevese ◽  
F. Schena
Keyword(s):  
Mathematical Model ◽  
Carotid Artery ◽  
Normal Pressure ◽  
Compressed Air ◽  
Whole Body ◽  
Body Acceleration ◽  
Vascular Bed ◽  
Pressure Changes ◽  
The Mathematical Model

In the present paper pressure changes induced by sudden body acceleration are studied “in vivo” on the dog and compared to the results obtainable with a recently developed mathematical model. A dog was fixed to a movable table, which was accelerated by a compressed air piston for less than 1 s. Acceleration was varied by changing the air pressure in the piston. Pressure was measured during the experiment at different points along the vascular bed. However, only data obtained in the carotid artery and abdominal aorta are presented here. The results demonstrated that impulse body accelerations cause significant pressure peaks in the vessel examined (about + 25 mmHg in the carotid artery with body acceleration of g/2). Moreover, pressure changes are rapidly damped, with a time constant of about 0.1s. From the present results it may be concluded that, according to the prediction of the mathematical model, body accelerations such as those occurring in normal life can induce pressure changes well beyond the normal pressure value.

scholarly journals Effect of a Commercial Air Valve on the Rapid Filling of a Single Pipeline: a Numerical and Experimental Analysis

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1814 ◽  
Author(s):  
Óscar E. Coronado-Hernández ◽  
Mohsen Besharat ◽  
Vicente S. Fuertes-Miquel ◽  
Helena M. Ramos
Keyword(s):  
Mathematical Model ◽  
Air Water Interface ◽  
Water Pipelines ◽  
Polytropic Equation ◽  
Pipeline Failure ◽  
Air Valve ◽  
Thermodynamic Variables ◽  
Air Pockets ◽  
The Mathematical Model ◽  
Oscillation Equation

The filling process in water pipelines produces pressure surges caused by the compression of air pockets. In this sense, air valves should be appropriately designed to expel sufficient air to avoid pipeline failure. Recent studies concerning filling maneuvers have been addressed without considering the behavior of air valves. This work shows a mathematical model developed by the authors which is capable of simulating the main hydraulic and thermodynamic variables during filling operations under the effect of the air valve in a single pipeline, which is based on the mass oscillation equation, the air–water interface, the polytropic equation of the air phase, the air mass equation, and the air valve characterization. The mathematical model is validated in a 7.3-m-long pipeline with a 63-mm nominal diameter. A commercial air valve is positioned in the highest point of the hydraulic installation. Measurements indicate that the mathematical model can be used to simulate this phenomenon by providing good accuracy.

scholarly journals Approximation of potential-driven flow dynamics in large-scale self-similar tree networks

2011 ◽  
Vol 467 (2134) ◽  
pp. 2810-2824 ◽  
Author(s):  
Jason Mayes ◽  
Mihir Sen
Keyword(s):  
Mathematical Model ◽  
Analytical Solutions ◽  
Large Scale ◽  
Differential Algebraic Equations ◽  
Flow Dynamics ◽  
Algebraic Equations ◽  
Tree Networks ◽  
Self Similar ◽  
Large Scale Flow ◽  
The Mathematical Model

Dynamic analysis of large-scale flow networks is made difficult by the large system of differential-algebraic equations resulting from its modelling. To simplify analysis, the mathematical model must be sufficiently reduced in complexity. For self-similar tree networks, this reduction can be made using the network’s structure in way that can allow simple, analytical solutions. For very large, but finite, networks, analytical solutions are more difficult to obtain. In the infinite limit, however, analysis is sometimes greatly simplified. It is shown that approximating large finite networks as infinite not only simplifies the analysis, but also provides an excellent approximate solution.

Modeling and Stability Analysis of Hydraulic System for Wave Simulation

2013 ◽  
Vol 291-294 ◽  
pp. 1934-1939
Author(s):  
Jian Jun Peng ◽  
Yan Jun Liu ◽  
Yu Li ◽  
Ji Bin Liu
Keyword(s):  
Mathematical Model ◽  
Stability Analysis ◽  
Mathematical Models ◽  
Hydraulic System ◽  
Simulation System ◽  
Displacement Sensor ◽  
Schematic Diagram ◽  
Wave Simulation ◽  
The Stability ◽  
The Mathematical Model

This thesis put forward a hydraulic wave simulation system based on valve-controlled cylinder hydraulic system, which simulated wave movement on the land. The mathematical model of valve-controlled symmetric cylinder was deduced and the mathematical models of servo valve, displacement sensor and servo amplifier were established according to the schematic diagram of the hydraulic system designed, on the basis of which the mathematical model of hydraulic wave simulation system was obtained. Then the stability of the system was analyzed. The results indicated that the system was reliable.

The Numerical Simulation of Directional Solidification Process Temperature Field for Large-Scale Frustum of a Cone Ingot

2011 ◽  
Vol 189-193 ◽  
pp. 1476-1481
Author(s):  
Kun Liu ◽  
Zhe Wang ◽  
Ren Zhi Han ◽  
Zi Ping Ren
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Temperature Field ◽  
Directional Solidification ◽  
Large Scale ◽  
Solidification Process ◽  
Directional Solidification Process ◽  
Ingot Quality ◽  
Fluent Software ◽  
The Mathematical Model

By using Fluent software, the mathematical model of temperature field is established on directional solidification process for large-scale frustum of a cone ingot, and the result is analyzed by Origin software, Tecplot. The influences of different width/thickness ratio to directional solidification process of cone ingot are discussed in order to provide basis for design optimization and ingot quality improvement.

Hydropneumatic Suspension Design

2003 ◽  
Author(s):  
Mauri´cio Baldi ◽  
Pable Siqueira Meirelles
Keyword(s):  
Mathematical Model ◽  
Hydraulic System ◽  
Experimental Validation ◽  
Crop Protection ◽  
Load Factor ◽  
Height Control ◽  
Suspension Parameters ◽  
High Dynamic ◽  
The Mathematical Model ◽  
Dynamic Load Factor

This study proposes a robust and cheap hydropneumatic suspension system for agricultural trailers used to spread crop protection. This kind of vehicle has a high dynamic load factor that increases the axles loads when it is in use and require a height control to assure the same spraying efficiency keeping constant the distance between the spray nozzles and the crop. As the tractor has its own hydraulic system, the hydropneumatic suspension conception take in account that height control will be done by the hydraulic fluid, being the mass of gas kept constant. A mathematical model of the hydropneumatic spring stiffness behavior was developed, as well as a methodology to define the suspension parameters. Experimental validation of the mathematical model was carried out through the use of a real agricultural trailer, equipped with a hydropneumatic suspension projected using the procedure presented, and tested in a hydropuls® road simulator.

scholarly journals The study of dynamic processes in the hydraulic system of the roll clamp of a two-cone unwinder rolls pipe-welding unit 159-529

2020 ◽  
Vol 2 (127) ◽  
pp. 25-44
Author(s):  
Igor Mazur ◽  
Dmitry Sheludko ◽  
Mykhailo Petrov
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Hydraulic System ◽  
High Reliability ◽  
Operating Experience ◽  
Dynamic Loads ◽  
Hydraulic Systems ◽  
Software Environment ◽  
Return Stroke ◽  
Pipe Welding

The work is devoted to the study of dynamic loads arising in the hydraulic system of the clamping mechanism of a roll of a two-cone unwinder of rolls of tubes of a pipe-welding unit 159-529. The operating experience of the two-cone unwinder has shown that one of its drawbacks is the unsatisfactory operation of the roll clamp hydraulic system, in which increased dynamic loads are observed. In the hydraulic system of the roll clamping mechanism, the executive hydraulic cylinder is located at a large distance from the pressure source, therefore, it uses long hydraulic lines. In transient modes of operation of a machine with such a hydraulic system, wave processes arise in it (unsteady fluid motion), which affect the quality of its functioning.Based on the analysis of mathematical models used in the practice of dynamic calculations of real hydraulic systems, it is shown that it is advisable to use a system of partial differential equations converted by a finite-difference method into a system as a mathematical model that takes into account the design and operation of the hydraulic system of the roll clamp mechanism of a two-cone unwinder ordinary differential equations with boundary conditions. This makes it possible to create a dynamic model that allows with high reliability to analyze the behavior of the hydraulic system of the mechanism of the clamping roll of a two-cone unwinder. During the implementation of the proposed mathematical model in the Simulink MATLAB software environment, a study was made of the operating modes of the hydraulic system of the roll clamping mechanism. As a result of the study, it was shown that in the hydraulic system of the roll clamping mechanism of a two-cone unwinder, dynamic loads occur at the end of the return stroke, which significantly exceed the permissible values.In order to reduce dynamic loads, a valve operating procedure with a response time of 0.16 seconds is proposed. This allows you to significantly reduce dynamic loads in the hydraulic system of the roll clamping mechanism by reducing the speed of movement of the hydraulic cylinders at the end of the carriage return stroke.

scholarly journals Development and Evaluation of Energy-Saving Electro-Hydraulic Actuator

Actuators ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 302
Author(s):  
Triet Hung Ho ◽  
Thanh Danh Le
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
Energy Saving ◽  
Energy Recovery ◽  
Hydraulic Systems ◽  
Hydraulic Actuator ◽  
High Effectiveness ◽  
Simulation Results ◽  
The Mathematical Model ◽  
Insight Into

This paper will develop a novel electro-hydraulic actuator with energy saving characteristics. This system is able to work in differential configurations through the shifting algorithm of the valves, meaning that this developed system can be adjusted flexibly to obtain the desirable working requirements including the high effectiveness of energy recovery from the load, high velocity or torque. Instead of establishing the mathematical model for the purpose of the dynamic analysis, a model of the developed actuator is built in AMESim software. The simulation results reveal that the system is able to save approximately 20% energy consumption compared with a traditional without energy recovery EHA. Furthermore, to evaluate the accuracy of the model, experiments will be performed that prove strongly that the experimental results are well matched to the results attained from the simulation model. This work also offers a useful insight into designing and analyzing hydraulic systems without experiments.

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