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    Experimental Investigation of a Monopropellant Thruster Using Hydrogen Peroxide

    , M.Sc. Thesis Sharif University of Technology Nikfar, Rouzbeh (Author) ; Farahani, Mohammad (Supervisor)
    Monopropellant thrusters are one of the most common types of propulsion systems that are used extensively in space applications. Especially thrusters with a capacity of less than 50N, they are used on space satellites and are developing rapidly. Problems such as contamination, toxicity of the propellant, difficulty in storing and custody, as well as price, led to the removal of the hydrazine from the focus of attention and focus on green propulsion. One of these, is the green propellant of hydrogen peroxide, which is decomposed in the proper catalytic vicinity, and the only chemical decomposition products are oxygen and water vapour. The present study aims to design and construct mono... 

    Numerical Study of Film Cooling in a Space Thruster

    , M.Sc. Thesis Sharif University of Technology Madani, Mohammad Reza (Author) ; Mardani, Amir (Supervisor)
    In high-performance liquid fuel motors and space thrusters, the combustion chamber and nozzle walls are in contact with the gases caused by high temperature and pressure combustion, making severe thermal loads on the walls. Therefore, these systems require cooling mechanisms. The most common way of cooling in space thrusters is film cooling. This study is a numerical simulation of film cooling in the liquid fuel space thrusters. Numerical and empirical studies have been reviewed in this area and evaluated while conducting studies and results to select an appropriate model for ongoing project studies. Along this path, various fuel and oxidizing thrusters, including oxygen and hydrogen,... 

    Synthesis and Evaluation of Nanostructured Photocatalysts for Oxidation Desulfurization of Liquid Fuels

    , M.Sc. Thesis Sharif University of Technology Abdollahi Arpanahi, Moslem (Author) ; Khorasheh, Farhad (Supervisor) ; Ghotbi, Sirous (Supervisor) ; Larimi, Afsaneh (Supervisor)
    In recent decades, desulfurization processes have become essential to decrease environmental pollution due to the emission of sulfur from fuels. In this study, in order to desulfurize liquid fuel, a model fuel (normal heptane) was investigated under visible light ) 350-watt sodium lamp(, using H2O2 as oxidant and methanol as a solvent in the presence of Cu-C-TiO2 nanostructure. C-TiO2 was synthesized by the hydrothermal method. In order to modify and improve the properties, we doped the copper metal by impregnation method with different loading of Cu. Experimental results exhibited the highest activity among samples attributed to 0.5% Cu-C-TiO2 Which caused 98.27% degradation of DBT after 2... 

    Oxidation Desulfurization of Liquid Fuels Using TiO2-based Photocatalysts

    , M.Sc. Thesis Sharif University of Technology Ostovar, Abdollah (Author) ; Khorasheh, Farhad (Supervisor) ; Larimi, Afsaneh Sadat (Supervisor)
    Due to the increasing consumption of fuel, the use of new methods with high efficiency to remove sulfur from fossil fuels is felt more than ever. Hydrogenation and oxidation of sulfur organic matter, such as thiophenes, is an old method of desulfurization of liquid fuels. Using a photocatalyst, everything can be done in an environment that is very low cost. In this study, the photocatalytic elimination of dibenzothiophene was investigated. For this purpose, carbon-doped thiamine dioxide was used as the photocatalytic base, which is synthesized by hydrothermal method. This method is the same source of titanium and carbon. To increase the performance of the catalyst, platinum metal was loaded... 

    Thermal Analysis of Regenerative Cooling in Liquid Rocket Engines

    , M.Sc. Thesis Sharif University of Technology Azizi, Mahdi (Author) ; Kebriaei, Azadeh (Supervisor)
    In this thesis to simulate the behavior of liquid engine Thrust chamber of hot gas from a quasi one dimensional code used when the effects of the heat transfer and friction in those terma. As well as during the regenerative channel is simulated by considering the equation’s of continuity, momentum and energy for one dimensional, effects of increase temperature, pressure drop, change the density of coolant flow resulting from the warming which is visible along the way to increase the accuracy of calculation of the thermal flux output of the engine, use a suitable model for unclear boiling in consideration of heat transfer coefficient used coolant flow it has been. As well as coupling of heat... 

    Fabrication and Evaluation of Nanostructured Photocatalysts Using Metal-Organic Frameworks for Photocatalytic Oxidative Desulfurization of Liquid Fuel

    , M.Sc. Thesis Sharif University of Technology Beshtar, Mehdi (Author) ; Khorasheh, Farhad (Supervisor) ; Ghotbi, Cirous (Supervisor) ; Larimi, Afsaneh (Supervisor) ; Asgharinejad, Ali Akbar (Co-Supervisor)
    Ti-UIO-66(Zr) nanocomposites have been prepared via a modified one-step solvothermal methodology and evaluated in photocatalytic oxidative desulfurization. Extensive characterization by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence spectroscopy (PL), nitrogen adsorption-desorption, and thermogravimetric analysis (TGA), have revealed the role of Ti loading, on Ti speciation and the structure of the composite materials. Their performance have been... 

    Investigation of fuel dilution in ethanol spray MILD combustion

    , Article Applied Thermal Engineering ; Volume 159 , 2019 ; 13594311 (ISSN) Motaalegh Mahalegi, H. K ; Mardani, A ; Sharif University of Technology
    Elsevier Ltd  2019
    MILD combustion is a promising technique for low heating value fuels. In this paper, spray MILD combustion of diluted liquid fuel is numerically studied. The modelling framework is based on the RANS approach, the EDC combustion model with a skeletal chemical mechanism, and the Lagrangian tracking of droplets. The validated numerical model is used to simulate the combustion of ethanol diluted with water is studied for different oxidizer temperatures and O2 concentrations under MILD condition. Results indicate that a low-level fuel dilution up to 5 percent has tendency toward expansion of MILD region, but higher degrees fuel dilution within the range of 5–20 percent results in a reduction of... 

    Three Dimensional Numerical Simulation of Slinger Combustor

    , M.Sc. Thesis Sharif University of Technology Akhtar Danesh, Mohammad Ali (Author) ; Farshchi, Mohammad (Supervisor)
    Annular combustion chambers used in small turbine motors which incorporate centrifugal (rotary) injectors for injecting fuel, are known as Slinger combustion chambers. The Slinger injector works in such a way that fuel enters from an inner tube in motor shaft and exits with high pressure from the holes on the cylinder connected to the shaft. Because of the high centrifugal force, the fuel is sprayed with high quality after entering the combustion chamber. Type and angle of spray, fuel-air mixing type, combustion phenomena and flame stability makes this different than other annular combustion chambers. The process of combustion in the Slinger chamber of YJ402 motor is numerically simulated in... 

    Theoretical and experimental modeling of vortex engine in ramjet application

    , Article 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 2 August 2009 through 5 August 2009, Denver, CO ; 2009 ; 9781563479762 (ISBN) Besharat Shafiei, S ; Ghafourian, A ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
    A new experimental facility was designed, fabricated and tested to model and study the possibility of applying the bidirectional swirl flow on the combustion chamber of airbreathing subsonic ramjet engine. Appropriate intake was designed to convert axial external air to tangential swirl flow inside the combustion chamber. Inlets with appropriate angles conduct the swirl flow into the chamber and create bidirectional swirl flow field in the combustion chamber. This flow field has been modeled theoretically to determine the velocity field characteristics by previous researchers. Bidirectional swirl flow in liquid fuel ramjet engines has the proven advantage of keeping the combustion chamber... 

    An experimental study on low temperature combustion in a light duty engine fueled with diesel/CNG and biodiesel/CNG

    , Article Fuel ; Volume 262 , 2020 Ghaffarzadeh, S ; Nassiri Toosi, A ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2020
    Low temperature combustion potentially can improve engine efficiency coupled with the benefits of low nitrogen oxides, and particulate matter emissions, and vice versa high unburned hydrocarbon and carbon oxide emissions through in-cylinder fuel reactions. In this survey, the experiments were carried out using a modified one-cylinder reactivity controlled compression ignition engine, dual-fueled diesel/compressed natural gas and biodiesel/CNG, to investigate the effects of direct injection strategies on the engine combustion efficiency and emission characteristics. Different ratios of biodiesel blends at different premixed ratios were applied to the dual-fuel engine. The results showed that...