Search for: hydraulics
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    Impact of Stress on Permeability of Packed Hydraulic Fracture

    , M.Sc. Thesis Sharif University of Technology Taherzadeh, Dadbeh (Author) ; Shad, Saeed (Supervisor) ; Fatemi, Mobeen ($item.subfieldsMap.e)
    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... 

    Intelligent Force Control for Hydraulic Manipulator within the Impedance Control Framework

    , M.Sc. Thesis Sharif University of Technology Alimohammadi, Hossein (Author) ; Khayyat, Amir Ali Akbar (Supervisor)
    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... 

    Investigating the Propagation of Thermal-hydraulic Noise in PWRs in Two phases

    , M.Sc. Thesis Sharif University of Technology Naghavi Dizaji, Davod (Author) ; Vosoughi, Naser (Supervisor)
    The core behaviour of a nuclear reactor might be fluctuated (deviations from the normal operating conditions) in operating conditions due to various reasons. Control rod vibrations and the alterations of coolant temperature and velocity could be the main reasons for the fluctuations. These fluctuations lead to neutronic flux noise and subsequently power noise. The main objective of the current thesis was to study the thermal-hydraulic noise of the PWRs in two-phase with the emphasis on VVER-1000, which is similar to the Bushehr-1 nuclear reactor. By considering the possibility of existing two-phase flow (maximum allowable quality is about 14%) in hot channel of the PWRs, thermal-hydraulic... 

    Simulation of Steam Bubble Collapse Induced Water Hammer (SBCIWH) in the Bushehr NPP Deaerator

    , M.Sc. Thesis Sharif University of Technology Saemi, Amir (Author) ; Ghofrani, Mohammad Bagher (Supervisor)
    Due to nuclear power plants’ growing roll in providing energy, analyzing probable accidents and their prevention is of vital importance. The thermal-hydraulic shock accident which happened in Bushehr nuclear power plant deaerator has been simulated in this study. Steam bubble collapsing which takes place in two phase medium by mixing steam and subcooled water leads to this kind of shock causing financial and physical irreparable damage in nuclear power plants. For carrying out this simulation, first an steady state model of the deaerator was run using RELAP5 code and then using this model and other plant’s data such as the ropert of the accident and plant’s Final Safety Analysis Report... 

    Neutronic and Thermal-Hydraulic Coupling in time domain and Feasibility Study of its Application in Accident Prediction

    , M.Sc. Thesis Sharif University of Technology Abbasi Fashami, Sajjad (Author) ; Vosoughi, Naser (Supervisor)
    Analysis of neutronic and thermal-hydraulics fluctuations has various applications in calculation or measurement of the core dynamical parameters (temperature reactivity coefficients) furthermore it is applicable in thermal-hydraulics surveillance and diagnostics. Experience of the Fukushima Dai-ichi plant and the lessons learned from the European stress tests, demonstrated that alternative and various tools and methods are needed for the reactor's condition identification. In this paper the feasibility of development of an alternative accident monitoring via eminent coupling of neutron and thermal-hydraulics noise is proposed. and it is programming a simple simulator for calculating... 

    Investigating the Propagation Noise in PWRs via Coupled Neutronic and Thermal-Hydraulic Noise Calculations

    , Ph.D. Dissertation Sharif University of Technology Malmir, Hessam (Author) ; Vosoughi, Naser (Supervisor)
    In operating nuclear reactor core, fluctuations (deviations from normal operating conditions) are usually produced and propagated. These fluctuations can be due to control rod vibrations, inlet coolant temperature fluctuations, inlet coolant velocity fluctuations and so on. The induced neutron noise can be detected by in-core neutron detectors. Noise source identifications (such as the type, location and propagating velocity) as well as the calculation of the dynamical parameters (such as moderator temperature coefficient in PWRs and Decay Ratio in BWRs) are of the main applications of the neutron noise analysis in power reactors.
    Investigating the propagation noise in PWRs (specifically... 

    Development of a Computer Code for Thermal Hydraulic Design of a High Temperature Gas Cooled Reactor Core

    , M.Sc. Thesis Sharif University of Technology Khosravi Mirzaee, Morteza (Author) ; Ghofrani, Mohammad Bagher (Supervisor) ; Jafari, Jalil (Supervisor)
    High temperature gas cooled reactors (HTGR) are one of the most promising reactors in the new generation of world commercial reactors. They are divided into two main categories: Prismatic gas cooled reactors and pebble bed gas cooled reactors. These reactors have many advantages, such as inherent safety, high thermodynamic efficiency and the possibility of producing hydrogen. One of the most important challenges in developing these reactors is providing appropriate codes in design and simulating their performance. Two codes have been developed in this thesis. The first, THFAM, is a steady state thermal hydraulic code which helps in analyzing a fuel assembly. The second, named THCM is... 

    Development of a Computer Code for Thermo Hydraulics Analysis of Prismatic High Temperature Gas Cooled Reactors

    , M.Sc. Thesis Sharif University of Technology Naderi, Mohammad Hossein (Author) ; Ghofrani, Mohammad Bagher (Supervisor) ; Jafari, Jalil (Supervisor)
    A prismatic high temperature gas-cooled reactor (HTGR), which is a graphite moderated, helium-cooled reactor, is a promising candidate for next generation nuclear power plant in that it enables applications, such as hydrogen production or process heat for petrochemical by supplying heat with core outlet temperatures as high as 1000°C. A Thermal Hydraulic Analysis Code (THAC) for gas-cooled reactors has been developed. THAC implicitly solves heat transfer equation of fuel, graphite block and helium. Three types of fuel pins were considered; solid fuel pin, fuel pins with inside holes and annular fuels with coolant flow from its inside and outside surfaces. THAC predicts axial and radial... 

    Modeling and Design Analysis of an Aircraft Longitudinal Reversible Flight Control System and its Enhancement to Irreversible One

    , M.Sc. Thesis Sharif University of Technology Ferdowsi, Mohammad (Author) ; Pourtakdoust, Hossien (Supervisor) ; Raeesi Charmkani, Kamran (Supervisor)
    Flight control system (FCS) design, analysis and modeling has an important role in aircraft design and development process. However, FCS analysis and studies are rarely focused at university levels and its know-how and technical issues are almost proprietary to various aircraft industries. One of the key goals of this thesis is to express, introduce and implement the processes that need to be followed for a sample longitudinal reversible FCS design (RFCS), where the modelling aspects are described for an existing aircraft. The latter is achieved using existing drawings, system and aerodynamic data of an existing aircraft utilizing commercial tools such as CATIA for initial design and ADAMS... 

    Development of a Multi-functional Soil Column for Studying Bioremediation and Multiphase Flow

    , M.Sc. Thesis Sharif University of Technology Samari, Peyman (Author) ; Sadeghi, Hamed (Supervisor)
    Soil and water pollution is one of the most common types of pollution in terrestrial and aquatic ecosystems. The development of mines and the oil and petrochemical industry on one hand and the non-compliance with environmental requirements on the other hand have caused large amounts of hydrocarbon pollutants and heavy metals to enter the environment in recent decades. Petroleum materials and heavy metals leak into the surrounding environment during drilling and extraction in oil sites and mines or during land and sea transportation, despite the measures taken to control their pollution. The conducted studies show that human industrial activities are the only cause of environmental pollution... 

    Impacts of Water Level Rise and Fall of a Hypersaline Lake on Seawater Intrusion: Case of Lake Urmia, Iran

    , M.Sc. Thesis Sharif University of Technology Ghazvini, Faezeh (Author) ; Ataie Ashtiani, Behzad (Supervisor)
    Lake Urmia located in the NW of Iran, has lost 96 percent of its volume in 20 years and become a national crisis. During this shrinkage, the lake level has fallen by 8 m, and its concentration has increased up to 380 g/l. Regarding the vast area Lake Urmia basin is covered, the hydrological characteristics of the basin varies a lot, which affects the aquifers response to the seawater intrusion. In order to study the seawater intrusion in the lake’s aquifer, 18 cases with different hydraulic gradients, hydraulic conductivities and bathymetries were defined. All of these cases were run under three different scenarios in sequence. First, steady state scenario is preformed, then the lake level... 

    Probabilistic Assessment of Flood Risk Using Data-Driven Flood Depth Modeling: A Case Study of Poldokhtar City

    , M.Sc. Thesis Sharif University of Technology Ziya Shamami, Oveys (Author) ; Safaie Nematollahi, Ammar (Supervisor)
    The present study aims to evaluate the flood risk of Poldokhtar city probabilistically using Monte Carlo Simulations (MCS). Two-dimensional (2D) models, which are highly accurate, have been used widely for flood modeling. However, they are not suitable for applications such as MCSs that need to be repeated many times or real-time flood forecasting applications, which require that flood inundation maps quickly be produced. In the current study, we developed a data-driven surrogate model based on the Least Squares Support Vector Machine (LS-SVM), a supervised machine learning method, to predict flood depth in order to simulate similar results to 2D hydraulic modeling. HEC-RAS was used for 2D... 

    Effects of Microstructure and Salinity Concentration on Hydraulic Conductivity of Silty Clay Soils

    , M.Sc. Thesis Sharif University of Technology Khodadadi, Saeed (Author) ; Sadeghi, Hamed (Supervisor)
    Various contaminants and their leachate, when they penetrate into the soil, cause changes in soil microstructure, this change in microstructure leads to changes in soil permeability and volume. In this study, first, the effects of soil microstructure change on the hydraulic conductivity of saturated soil were investigated using the change in initial saturation degree during compaction for compacted samples and the change in sample construction in reconstituted samples. Also, the simultaneous effect of changing the initial microstructure and salt solution on the hydraulic conductivity of saturated silty clay soils using a three-axial permeability device with the ability to measure volume... 

    Development of a High-precision Unsaturated Permeameter for Characterizing Two-phase Flow Through Deformable Porous Media

    , M.Sc. Thesis Sharif University of Technology Hassani Motlagh, Amin (Author) ; Sadeghi, Hamed (Supervisor)
    Given that highly deformable natural deposits such as collapsible and swelling soils make up more than one-fifth of the land surface and are generally in unsaturated conditions, behavioral measurement of this type of soil including accurate measurement of its hydraulic properties is important. The challenges of designing and implementing construction infrastructure, along with the most reported financial losses due to the presence of these soils, double the importance of studying the behavior of these soils. The large volume changes of these soils in contact with water (equivalent to a volumetric strain of more than 5%) has been a major challenge for researchers in predicting the... 

    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 Golaghaei Darzi, Ali (Author) ; Sadeghi, Hamed (Supervisor)
    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... 

    Laboratory Investigation of the Effects of Sodium Chloride Concentration on Soil Water Retention Curve and Volumetric behavior Using an Unsaturated Automatic Oedometer

    , M.Sc. Thesis Sharif University of Technology Nasiri, Hamed (Author) ; Sadeghi, Hamed (Supervisor)
    Laboratory studies to investigate the effects of different saline concentrations (such as sodium chloride or calcium chloride) on the soil water retention behavior of clayey soils and their volumetric changes have received much attention recently. However, many previous studies have investigated these effects in only one path of the SWRC (wetting or drying path) and the effects of saline concentration on hydraulic hysteresis have not been considered. In addition, researchers have frequently studied these effects on SWRC on clay samples, and little research has been done on collapsible soils. Therefore, the most important purpose of this study is to investigate the effects of increasing... 

    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 Khojeh, Shokoufeh (Author) ; Ataie Ashtiani, Behzad (Supervisor)
    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... 

    Study of the Effects of Geo-mechanical and Hydro-mechanical Parameters on Hydraulic Fracturing Characteristics in Oil Reservoirs by Numerical Modeling

    , M.Sc. Thesis Sharif University of Technology Esfandiari, Morteza (Author) ; Pak, Ali (Supervisor)
    Increasing the permeability of hydrocarbon reservoirs by creating artificial cracks that are induced by injection of fluids under high pressures is called Hydraulic Fracturing operation. This method is widely used in petroleum reservoir engineering. For design of Hydraulic Fracture operations, a number of methods have been developed. KGD and PKN are the first and most used methods in this area and despite the development of advanced softwares in recent years, these methods are still popular and are used in a number of softwares. KGD is commonly used for induced fractures where the height of fracture is greater than its length, and PKN is normally used where the length of the fracture is... 

    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 Iranmanesh, Mohammad Ali (Author) ; Pak, Ali (Supervisor)
    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... 

    Numerical Modeling of Fluid Flow and Proppant Transport in Hydraulic Fracture Using Extended Finite Element Method

    , Ph.D. Dissertation Sharif University of Technology Hosseini, Navid (Author) ; Khoei, Amir Reza (Supervisor) ; Shad, Saeed (Co-Supervisor)
    Transport phenomena in porous media play important role in many areas of subsurface hydrology, geo-physics, environment, energy and petroleum. The work in the field of numerical modeling of fractured porous media is yet an open area of research. The classic finite element method (FEM) has some limitations in modeling of discontinuities like fracture. FEM mesh should conform with the geometry of the fracture. Presence of fracture imposes discontinuity in pressure field of fluid phases and displacement field of solid phase (rock). To represent the fractures, the extended finite element method (X-FEM) can be used in which the standard finite element approximation of the field variables is...