Loading...
Search for:
karimi-motaalegh-mahalegi--hamed
0.111 seconds
Total 729 records
Ethanol spray combustion under a MILD condition: a chemical kinetic study
, Article Energy and Fuels ; Volume 33, Issue 11 , 2019 , Pages 11861-11886 ; 08870624 (ISSN) ; Mardani, A ; Sharif University of Technology
American Chemical Society
2019
Abstract
Moderate or intense low-oxygen dilution (MILD) combustion of liquid fuels has attracted attention because of its advantages in industrial burners and gas turbine applications. Here, numerical investigation has been conducted on an experimental MILD turbulent spray burner. The H∥ flame of Delft spray in a hot co-flow burner is selected, and the Reynolds averaged Navier-Stokes/eddy dissipation concept framework with 40 species/180 reversible reactions through a skeletal chemical mechanism is used in addition to unsteady Lagrangian tracking of spray droplets to investigate the flame structure and chemical kinetic of reacting flow field. At first, current numerical results were compared with...
Corrigendum to “Investigation of fuel dilution in ethanol spray MILD combustion” [Appl. Therm. Eng. 159 (2019) 113898] (Applied Thermal Engineering (2019) 159, (S1359431118371308), (10.1016/j.applthermaleng.2019.113898))
, Article Applied Thermal Engineering ; Volume 180 , November , 2020 ; Mardani, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The authors regret to inform that the corresponding author is altered from Hamed Karimi Motaalegh Mahalegi to Amir Mardani with the email address of: Amardani@sharif.edu updated as above. The authors would like to apologise for any inconvenience caused. © 2020 Elsevier Ltd
Structure of the ethanol spray flame under conventional and MILD conditions
, Article Fuel ; Volume 321 , 2022 ; 00162361 (ISSN) ; Mardani, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
A numerical examination is carried out on the experimental MILD turbulent spray burner of Delft Spray in Hot Co-flow, DSHC. The RANS approach is combined with the Lagrangian tracking of droplets for modeling the pressure-swirl atomizer. The EDC combustion model is employed, to take into account detailed chemical mechanisms. Predictions show that the structure of the triple-flame of liquid fuel in the atmospheric condition is different from the conventional gaseous triple-flames. Furthermore, the structure of the MILD spray flame is compared to the non-MILD spray flame. The flame index shows that the triple-flame structure in the conventional spray flame that consists of two outer and middle...
An experimental study on kerosene spray combustion under conventional and hot-diluted conditions
, Article Combustion Science and Technology ; 2021 ; 00102202 (ISSN) ; Azimi, A ; Karimi Motaalegh Mahalegi, H ; Sharif University of Technology
Bellwether Publishing, Ltd
2021
Abstract
The combustion of kerosene spray under hot-diluted conditions and conventional conditions was experimentally investigated. By examining flame photographs, chemiluminescence images, and in-field temperature measurements, the separate effect of different variables including oxygen concentration, temperature and velocity of the co-flowing air, fuel flow rate and injection pressure, and eventually the type of spray nozzle on multiple parameters such as flame stability, structure, luminosity, temperature field, and qualitative CH radical distribution, as well as HCO and NO2 with lower precision, in the reaction region, have been studied. It was observed that an increment in injection pressure and...
An experimental study on kerosene spray combustion under conventional and hot-diluted conditions
, Article Combustion Science and Technology ; Volume 194, Issue 13 , 2022 , Pages 2712-2751 ; 00102202 (ISSN) ; Azimi, A ; Karimi Motaalegh Mahalegi, H ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
The combustion of kerosene spray under hot-diluted conditions and conventional conditions was experimentally investigated. By examining flame photographs, chemiluminescence images, and in-field temperature measurements, the separate effect of different variables including oxygen concentration, temperature and velocity of the co-flowing air, fuel flow rate and injection pressure, and eventually the type of spray nozzle on multiple parameters such as flame stability, structure, luminosity, temperature field, and qualitative CH radical distribution, as well as HCO and NO2 with lower precision, in the reaction region, have been studied. It was observed that an increment in injection pressure and...
Numerical Investigation of Turbulent Spray Combustion in Hot Diluted Co-Flow
, Ph.D. Dissertation Sharif University of Technology ; Mardani, Amir (Supervisor)
Abstract
The Moderate or Intense Low-oxygen Dilution (MILD) combustion of liquid fuels has attracted attention to use its advantages in industrial burners and gas turbines applications. Here numerical investigation has been conducted on a research experimental MILD turbulent spray burner (Deft Spray in Hot Co-flow, DSHC). RANS approach has been adopted for modeling of the reactive turbulent flow field of continues phase with the Lagrangian approach for droplet modeling of pressure-swirl atomizer fuel spray. The EDC combustion model is used which has the ability to take into account the detailed chemical mechanisms. The accuracy of different turbulence and droplet injection sub-models are examined and...
Investigation of fuel dilution in ethanol spray MILD combustion
, Article Applied Thermal Engineering ; Volume 159 , 2019 ; 13594311 (ISSN) ; Mardani, A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
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...
Hydrogen enrichment of methane and syngas for MILD combustion
, Article International Journal of Hydrogen Energy ; Volume 44, Issue 18 , 2019 , Pages 9423-9437 ; 03603199 (ISSN) ; Karimi Motaalegh Mahalegi, H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Moderate or Intense Low-oxygen Dilution (MILD) combustion is a technology with important characteristics such as significant low emission and high-efficiency combustion. The hydrogen enrichment of conventional fuels is also of interest due to its favorable characteristics, such as low carbon-containing pollutants, high reaction intensity, high flammability, and thus fuel usage flexibility. In this study, the effects of adding hydrogen to methane and syngas fuels have been investigated under conditions of MILD combustion through numerical simulation of a well-set-up MILD burner. The Reynolds-Averaged Navier-Stokes (RANS) approach is adopted along the Eddy Dissipation Concept (EDC) combustion...
Nonlinear Vibration Analysis of Non-Uniform Beam in two Lateral Directions by Multiple Scales Method: Application in Wind Turbine
, M.Sc. Thesis Sharif University of Technology ; Moradi, Hamed (Supervisor)
Abstract
Environmental issues and energy crisis have led the world attention to the renewable energies; especially wind power, since they have low cost and high reliability. One of the most challenging areas of studying for wind power is to increase the capacity of wind turbines. As a result, over the years, wind turbines have got progressively larger. Vibration is one of the problems that reduces the life and efficiency of wind turbines; and the growing size of the blades has worsen this problem due to the importance of nonlinear effects in large scale wind turbines. Researchers have been constantly working on this issue in order to make the wind turbines more efficient. In this research, a...
Modeling and Sliding Mode Control of a Roll-Pitch Seeker
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor) ; Pourtakdoust, Hossein (Supervisor) ; Mohammad Karimi, Hamed (Co-Supervisor)
Abstract
The purpose of this thesis is sliding mode control of a roll-pitch seeker by considering the zenith pass problem. This problem takes place when the target appears in front of the seeker’s head. First, the mathematical model of the roll and pitch frames is obtained by the Newton-Euler equations of motion. Then, a MIMO sliding mode controller is designed. The performance of the controller is investigated in the presence of model uncertainties and seeker disturbances. The results indicate that the designed controller is robust enough and provides a suitable performance in the stabilization, tracking and guidance loops.
An efficient tabu search algorithm for the single row facility location problem [electronic resource]
, Article European Journal Of Operational Research ; Vol. 205, No. 1, pp. 98-105 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
The general goal of the facility layout problem is to arrange a given number of facilities to minimize the total cost associated with the known or projected interactions between them. One of the special classes of the facility layout problem is the Single Row Facility Layout Problem (SRFLP), which consists of finding an optimal linear placement of rectangular facilities with varying dimensions on a straight line. This paper first presents and proves a theorem to find the optimal solution of a special case of SRFLP. The results obtained by this theorem prove to be very useful in reducing the computational efforts when a new algorithm based on tabu search for the SRFLP is proposed in this...
Sensitivity analysis of matching pennies game [electronic resource]
, Article Mathematical and Computer Modelling ; Volume 51, Issues 5–6, March 2010, Pages 722–735 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
In this paper, we have discussed the results of sensitivity analysis in a payoff matrix of the Matching Pennies game. After representing the game as a LP model, the sensitivity analysis of the elements of the payoff matrix is presented. The game value and the optimal strategies for different values of parameters are determined and compared
Parametric study and computation of seismic performance factors of braced shear panels
, Article Scientia Iranica ; Volume 23, Issue 2 , 2016 , Pages 460-474 ; 10263098 (ISSN) ; Mofid, M ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
By locating a steel shear panel on the intersection point of the X-braces, concentrically or eccentrically braced shear panel (CBFSP or EBFSP) is formed. In this paper, to perform parametric study, 1-story CBFSP and EBFSP models with span length greater or less than height are considered. Using linear static analyses, the effects of size and location of the shear panel on the lateral stiffness of the frame with respect to the moment resisting frame with the same member sections are investigated. Next, for 1- And 3-story models, maximum displacement, along with base shear, and the ratio between the dissipated energy and input energy are examined under 4 ground motion records. Behavior of the...
Assessment of Seismic Retrofit Policies for Buildings
, M.Sc. Thesis Sharif University of Technology ; Kashani, Hamed (Supervisor)
Abstract
Occurrence of natural disasters such as earthquake could seriously damage most buildings especially those with insufficient resistance located in urban worn-out textures. In order to reduce unpleasant consequences of an earthquake, appropriate policies need to be considered to persuade the beneficiaries to follow retrofitting standards in the process of planning, designing, and construction of buildings. These policies shall be implemented through institutions in arbitrary or obligatory forms, by encouragement or penalty mechanisms. In order to consider these policies, first of all we need to identify the beneficiaries and their particulars. By studying and considering subjects discussed in...
Optimal-Robust Control of Drug Delivery in Cancer Chemotherapy
, M.Sc. Thesis Sharif University of Technology ; Moradi, Hamed (Supervisor)
Abstract
Chemotherapy is a proven and effective systematic approach to treat various types of cancers. Despite its advantages, chemotherapy would kill healthy as well as cancer cells. To overcome this problem, different controlling strategies are implemented. This study aims to provide a medicine drug delivery schedule for chemotherapy (by designing a proper controlling system) based on the verifiable mathematical models. First, the dynamic model is analysed and stability points are reviewed. The selected model has five state variables and two inputs. In this study, the focus is on dynamic model analysis and obtaining an effective and appropriate treatment pattern by designing a proper controller. To...
Real Options Analysis Framework for the Optimal Timing of Network Infrastructure Systems Retrofits
, M.Sc. Thesis Sharif University of Technology ; Kashani, Hamed (Supervisor)
Abstract
Natural disasters can damage the infrastructure of society. Damages to the infrastructure components of society can disrupt their service delivery. Disruption in providing services to society's infrastructure can disrupt social and economic activities and impose various significant costs on society. The cost of repairing the damaged infrastructure and reducing the income of households are among the economic damages of accidents. The decline in the quality of life, as well as the death and injury of people due to the breakdown of the infrastructure or the disruption in their services, are among the social damages caused by accidents. In the same way, natural disasters are considered a...
Analysis of Seismic Vulnerability Reduction Policies of Residential Buildings Using a Multi-agent Evolutionary Game Model Based on Prospect Theory
, M.Sc. Thesis Sharif University of Technology ; Kashani, Hamed (Supervisor)
Abstract
Due to the vulnerability of urban fabric and residential buildings to earthquakes and considering its destructive social and economic effects on society, the need to adopt appropriate policies to prevent and reduce vulnerability, has been increasingly considered by policy makers. Despite the laws, regulations, incentives and penalties that policymakers have envisioned to prevent unprincipled and unsafe construction, evidence shows that a significant number of new buildings being built in the country are not earthquake resistant and there are many violations in design, implementation and supervision that is done by the stakeholders. To solve this problem, research has been done on the...
Development of a Multi-functional Soil Column for Studying Bioremediation and Multiphase Flow
, M.Sc. Thesis Sharif University of Technology ; Sadeghi, Hamed (Supervisor)
Abstract
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...
Developing Novel Algorithms to Simultaneous Power Regulation and Load Mitigation of Modern Variable Speed Wind Turbines
, Ph.D. Dissertation Sharif University of Technology ; Moradi, Hamed (Supervisor)
Abstract
The power control of horizontal axis wind turbines can affect significantly the vibration loads and fatigue life of the tower and the blades. In this thesis, we are going to consider both the power control and vibration load mitigation of the tower fore-aft vibration. For this purpose, at first, we developed a fully coupled model of the NREL 5MW turbine. This model considers the full aeroelastic behavior of the blades and tower and is validated by experiment results, comparing the time history data with the FAST (Fatigue, Aerodynamics, Structures, and Turbulence ) code which is developed by NREL (National Renewable Energy Lab in the United States). In the next, to estimate EWV, a novel...
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 ; Sadeghi, Hamed (Supervisor)
Abstract
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...