Search for: hydraulics
Total 319 records
Data-driven model-free control of torque-applying system for a mechanically closed-loop test rig using neural networks, Article Strojniski Vestnik/Journal of Mechanical Engineering ; Volume 66, Issue 5 , 2020 , Pages 337-347 ; Mardani, M ; Sharif University of Technology
Assoc. of Mechanical Eng. and Technicians of Slovenia 2020
This paper presents a data-driven approach that utilizes the gathered experimental data to model and control a test rig constructed for the high-powered gearboxes. For simulating a wide variety of operational conditions, the test rig should be capable of providing different speeds and torques; this is possible using a torque-applying system. For this purpose, Electro-Hydraulic Actuators (EHAs) are used. Since applying accurate torque is a crucial demand as it affects the performance evaluation of the gearboxes, precise modelling of the actuation system along with a high-performance controller are required. In order to eliminate the need for to solve complex nonlinear equations of EHA that...
Numerical modeling of hydraulic fracturing in oil sands, Article Scientia Iranica ; Volume 15, Issue 5 , 2008 , Pages 516-535 ; 10263098 (ISSN) ; Chan, D. H ; Sharif University of Technology
Sharif University of Technology 2008
Hydraulic fracturing is a widely used and efficient technique for enhancing oil extraction from heavy oil sands deposits. Application of this technique has been extended from cemented rocks to uncemented materials, such as oil sands. Models, which have originally been developed for analyzing hydraulic fracturing in rocks, are in general not satisfactory for oil sands. This is due to a high leak-off in oil sands, which causes the mechanism of hydraulic fracturing to be different from that for rocks. A thermal hydro-mechanical fracture finite element model is developed, which is able to simulate hydraulic fracturing under isothermal and non-isothermal conditions. Plane strain or axisymmetric...
A novel design and performance optimization methodology for hydraulic Cross-Flow turbines using successive numerical simulations, Article Renewable Energy ; Volume 169 , 2021 , Pages 1402-1421 ; 09601481 (ISSN) ; Durali, M ; Khakrand, M. H ; Hoghooghi, H ; Sharif University of Technology
Elsevier Ltd 2021
This paper introduces a new methodology for designing and optimizing the performance of hydraulic Cross-Flow turbines for a wide range of operating conditions. The methodology is based on a one-step approach for the system-level design phase and a three-step, successive numerical analysis approach for the detail design phase. Compared to current design methodologies, not only does this approach break down the process into well-defined steps and simplify it, but it also has the advantage that once numerical simulations are conducted for a single turbine, most of the results can be used for an entire class of Cross-Flow turbines. In this paper, after a discussion of the research background, we...
Numerical Simulation of Hydraulic Fracturing in Porous Media Considering Two Phase Flow and Thermal Effects Using Mesh-less XEFG Method, Ph.D. Dissertation Sharif University of Technology ; Pak, Ali
In this study, a fully coupled three-dimensional numerical analysis of two-phase fluid flow and heat transfer through deformable porous media is presented in the context of extended element free Galerkin method. By coupling momentum balance equation for the whole mixture, continuity equations of wetting and non-wetting fluid phases and energy balance equation, the developed numerical algorithm is capable of simulating a wide range of engineering problems such as CO2 sequestration, nuclear waste disposal in deep underground strata, hydraulic fracturing in oil and gas reservoirs and so on.By taking the advantages of partition of unity property of MLS shape functions, weak and strong...
Elitist continuous ant colony optimization algorithm for optimal management of coastal aquifers, Article Water Resources Management ; Volume 25, Issue 1 , 2010 , Pages 165-190 ; 09204741 (ISSN) ; Ketabchi, H ; Sharif University of Technology
This paper presents an evolutionary based approach to achieve optimal management of a coastal aquifer to control saltwater intrusion. An improved Elitist Continuous Ant Colony Optimization (ECACO) algorithm is employed for optimal control variables setting of coastal aquifer management problem. The objectives of the optimal management are; maximizing the total water-pumping rate, while controlling the drawdown limits and protecting the wells from saltwater intrusion. Since present work is one of the first efforts towards the application of an ECACO algorithm, sharp interface solution for steady state problem is first exploited. The performance of the developed optimization model is evaluated...
Effects of unsteady friction factor on gaseous cavitation model, Article Scientia Iranica ; Volume 17, Issue 1 B , 2010 , Pages 13-24 ; 10263098 (ISSN) ; Firooz Abadi, B ; Sharif University of Technology
The condition known as a water-hammer problem is a transient condition that may occur as a result of worst-case loadings, such as pump failures, valve closures, etc. in pipeline systems. The pressure in the water hammer can vary in such a way that in some cases it may increase and cause destruction to the hydraulic systems. The pressure in the water hammer can also be decreased to the extent that it can fall under the saturation pressure, where cavitation appears. Therefore, the liquid is vaporized, thus, making a two-phase flow. This pressure decrease can be as dangerous as the pressure rise. As a result of the pressure drop and vaporization of the liquid, two liquid regions are separated,...
Pressure and rate transient modeling of multi fractured horizontal wells in shale gas condensate reservoirs, Article Journal of Petroleum Science and Engineering ; Volume 185 , 2020 ; Taghavinejad, A ; Razghandi, M ; Rahimi Rigi, H ; Moeini, K ; Jamshidi, S ; Sharifi, M ; Sharif University of Technology
Elsevier B.V 2020
Gas condensate production using technology of multi-stage hydraulically fracturing in shale gas condensate reservoirs' horizontal wells is a new topic of unconventional resources studies. Thus, shale gas condensate as a new source of energy can be considered as an important issue for development and further studies. In this work, a semi-analytical solution of gas and oil two-phase flow is presented for pressure transient analysis (PTA) and rate transient analysis (RTA) of a shale gas condensate reservoir's production data. Fluid flow assumption here is flow in a pseudo triple-porosity porous media, which are matrix, natural fractures and adsorbed gas. Adsorbed gas is a form of gas in porous...
Model predictive control of a hydraulic actuator in torque applying system of a mechanically closed-loop test rig for the helicopter gearbox, Article Aviation ; Volume 23, Issue 4 , 2020 , Pages 143-153 ; Mardani, M ; Sharif University of Technology
Vilnius Gediminas Technical University 2020
Transmission health is an important factor in safety and maintenance costs in industries, so construction of test rigs for testing high-powered gearboxes under different operating conditions of helicopters is required. The studied test rig, which is developed at Sharif University of Technology branch of ACECR (Academic Centre of Education, Culture and Research) is mainly used for testing high-powered gearboxes through a mechanically closed-loop procedure. For providing a variety of speeds and torques in test rigs, torque applying system is required. According to generation of higher forces, reduced size of equipment and accurate positioning, electro hydraulic actuators (EHAs) are used for...
Experimental Investigation On Pressure Flactuation And Hydrulic Charectrics Of Two Phase Flow In Rectangular Inclined Tunnels, M.Sc. Thesis Sharif University of Technology ; Borgee, Mahmoud
Two phase slug flow often happens in culvert and water tunnels conveying water from dams and weirs. Having complicated hydraulic properties, little is known about different hydraulic properties of this kind of flow, while most of the previous studies deal with other liquids than water and air, mostly dealing with chemical and mechanical engineering problems. In this paper, the results from experimental study of air/water slug flow due to changing in slope of the conduit from horizontal to 2, 3 and 4% are presented. The conduit has rectangular cross section with dimension cm of Plexiglas material and inclined part. Air is added to the system upstream of the conduit using an air discharge....
Controlling Local Scour Due to Hydraulic Jump Using Oblique Buried Plates
Sharif University of Technology
Local scouring at the downstream of sluice gates in the erosive beds is one of the main concerns of hydraulic engineers because of the significant damage that it can cause to the hydraulic structures. It is important to control the local scour depth at downstream of hydraulic structures to ensure safety operation of these systems. Many researchers have conducted various studies to predict the maximum depth and diameter of scour hole and develop new methods in order to control this phenomenon. One way to overcome this problem is the use of apron, or non-erosive bed. In order to shorten the apron length or decrease the effect of the...
Development of an Improved Semi-active Damper Based on the Reduction of the Effects of Brace Flexibility, M.Sc. Thesis Sharif University of Technology ; Ahmadizadeh, Mehdi
Considerable research work has been dedicated to the development of structural control systems to improve the performance of structures and reduce the casualties resulting from earthquakes. It is generally accepted that semi-active control systems result in better structural performance compared to what can be achieved using passive systems. However, it has been observed that the majority of the performance improvement obtained from semi-active control systems stems from the reduction of brace flexibility effects, rather than the control algorithm used. In this study, it is attempted to utilize this fact to improve the performance of passive control systems, or develop simple semi-active...
Underbalanced Drilling Hydraulics Modeling and Optimization, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Saeid ; Pishvaie, Mahmoud Reza
Due to the underbalanced drilling advantages compared to the overbalanced drilling, this drilling method usage is on rise day to day. In this method, the well pressure has to be lower than formation pressure. To achieve this goal, we have to use light fluids such as air, foam, aerated mud, etc. Because of the compressible nature of these fluids, their hydraulics calculation is more complicated than overbalanced drilling fluids. Due to this complexity, a simulator which can predict and optimize the well conditions is very important in designing drilling schedule. In this thesis, by combination of different rheology and pressure drop equations for the foam, a simulator is developed to model...
Intelligent Force Control for Hydraulic Manipulator within the Impedance Control Framework, M.Sc. Thesis Sharif University of Technology ; Khayyat, Amir Ali Akbar
The main concept of this thesis is to simulate, develop, and analyze the performance of force control method by applying to a Unimate MK-II hydraulic manipulator. In this investigation, simulation studies are based on the concept of impedance control technique. Position-based formulation of impedance control is employed. First in this research, a PID controller is employed and is shown to be capable of performing position control task precisely despite the fact that inertia, joint stiction, valve deadband and other nonlinearities are presented. Although trajectory tracking is performed well after several investigations, we have concluded that the impedance control cannot perform a desirable...
Modeling of Hydraulic Fracture Propagation in Fractured Non-isothermal Saturated Porous Media with XFEM, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza
Investigation about Hydraulic Fracturing phenomenon in fractured porous medium which was occurred by in-situ fracture pressure upon the crack wings, owes the fact that creating enormous damages. However, it might include advantages such as increasing the rate of crude oil production from deep and high pressure/ high temperature reservoirs. On account of the fact that, existence of cracks and natural discontinuities and heat sources such as boundary of geo thermal reservoirs in porous mediums it is undeniable fact. Also, cross sectioning hydraulic fracturing cracks with natural cracks it is an obvious impact. Actually, investigation and analyzing the break throw of HF crack with natural...
Hydraulic Fracturing Modeling in Conventional and Unconventional Reservoirs, M.Sc. Thesis Sharif University of Technology ; Badakhshan, Amir ; Ghotbi, Siroos ; Taghikhani, Vahid
Unconventional fracturing applications such as long-term waterflooding at fracturing pressure, produced water re-injection and waterfracs, etc., are characterized by very high fluid leakoff velocity, long operation time and significant changes in stress, pore pressure, and/or permeability and porosity, affecting possibly large regions around the wellbore and/or fracture. These special characteristics make fracturing modeling methods developed for conventional fracturing applications inadequate. Some of the problems encountered include grid effects resulting in oscillation of fracture growth with time (limiting the stability of conventional fracture modeling models), singularity of material...
Identification Dynamic Modeling and Analysis of a Variable Displacement Axial Piston Pump, M.Sc. Thesis Sharif University of Technology ; Salarieh, Hassan
According to high nominal pressure and controllable flow, variable displacement axial piston pumps are used widely in hydraulic industry. However, there still exist many problems and limitations in the areas of design, controllers and performance. To solve the problems without wasting time and money in making prototypes, an accurate dynamic model of the pump is required which predicts pump behavior under various control signals and loads. The lack of simple and practical methods of measuring describing parameters of pump dynamics, makes investigation and verification of such a model very challenging. In this thesis, literature review is presented in a wide range. After investigating of...
Design for Fabrication of a Knee Prosthesis Wear Simulator, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad
Total knee replacement surgery is the most common joint replacement in the world. Considering the increasing rate of this procedure and costs and difficulties of the repeated operation, many efforts have been made to improve the performance and lifetime of implants. The Polyethylene component of the implant is the most prone component to fail due to wear. To evaluate new knee prosthesis designs, it is necessary to have a wear test simulator. Objective of this project is to detail design a knee prosthesis wear simulator according to ISO 14243 in order to investigate the performance of prosthesises in long term and under in-vivo conditions. During this project, studies have been made to get...
Impact of Stress on Permeability of Packed Hydraulic Fracture, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed ; Fatemi, Mobeen
Given the broad role of oil and gas playing in the world economy, finding the hydrocarbon reservoir that economically is affordable is quite significant. Some of the unconventional oil and gas reservoirs are important from the economic point of view since they produce insufficient hydrocarbon due to either low permeability or damage during drilling and production. Hydraulic fracturing is one of the most significant methods for improving the productivity of wells and reservoirs. Hydraulic fracturing acts by affecting on reservoir rock physic. In the current century, this approach has an essential effect in enhancing the permeability and production of reservoirs by creating, extending and...
Effect of DEM Resolution on Hydraulic Modeling of Flood Inundation Area: Case Study of Gorganrood River, Northeast of Iran, M.Sc. Thesis Sharif University of Technology ; Ataie Ashtiani, Behzad
Digital Elevation Models (DEM) is a crucial element of hydraulic models, including floods. Due to the lack of high-precision topographic data, including ground-based mapping hydraulic modeling is challenging. In recent years, remote sensing data, extensively used by many researchers in hydraulic modeling due to global coverage and free access. One of the most critical questions in hydraulic modeling is the efficiency of these DEMs in flood simulation. This research focused on using remote-sensing-based DEMs, such as SRTM-30m and 90m, ASTER-30m, and ALOS-12.5m DEMs, on the performance of the HEC-RAS-2D model in the Gorganrood river.The results showed that ALOS and SRTM-30m DEMs' accuracy and...
Development of a New Analytical Model based on Soil-water Retention Curve Microstructure Considering the Effects of Osmotic Potential, M.Sc. Thesis Sharif University of Technology ; Sadeghi, Hamed
The soil-water retention curves (SWRC) is an unsaturated soil mechanics hydro chemical state surface, which expresses the relationship between the soil suction and water content. The soil-water retention curve could describe the water adsorption and desorption process that happened in soils. The difference between the desorption or drying retention curve and the adsorption or wetting retention curves in a specific soil specimen indicates the hydraulic hysteresis phenomenon. Generally, the amount of water remaining in the drying process is greater than the amount of water adsorbed in the wetting process at a certain amount of suction. Suction due to the combined effects of capillary and...