Design and Optimization of Carbon Capture System from Exhaust Gases in the Process Industries

, M.Sc. Thesis Sharif University of Technology Farshi Taghavi, Mahdis (Author) ; Rashtchian, Davood (Supervisor) ; Seif, Shayan (Co-Supervisor)

Abstract

Carbon dioxide is one of the main geenhouse gases emitted from factories as well as transportation vehicles that adversely affect the atmosphere and cause global warming. Among the proposed solutions to reduce carbon dioxide in the atmosphere, carbon dioxide separation would be the most viable medium-term approach. However, the high cost of carbon dioxide separation prevents the development of carbon dioxide absorption technologies. Therefore, it seems that integrating separation and production processes is the most efficient way to save energy and reduce carbon emissions. This method decrease a high proportion of the energy consumption in upstream operations (carbon dioxide removal,...

Aerodynamic Design of 100 kW Transonic Ducted Fan

, M.Sc. Thesis Sharif University of Technology Shayan Fakhr, Atefeh (Author) ; Ghorbanian, Kaveh (Supervisor)

Abstract

The purpose of this research is the aerodynamic design of a 100 kW transonic ducted fan. Today, the aviation industry is moving towards the design of electric driven aircraft propulsion. Transonic ducted fans are one of the viable options that have been used in medium and heavy aircrafts due to their high specific power. In this research, the meanline model has been used for the initial design. By applying the design constraints, design limitations, design and functional parameters, the initial design point is found and then a sensitivity analysis is performed with respect to the effective design parameters to obtain the optimal design point. For the initial design of the transonic ducted...

Techno-Economic Comparison of Different Gas Turbine Inlet Cooling Techniques

, M.Sc. Thesis Sharif University of Technology Shayan, Mahdi (Author) ; Hakkaki Fard, Ali (Supervisor)

Abstract

Inlet air cooling is a simple and economical method to increase the power output of gas turbines. High-pressure fogging systems and mechanical chillers are two common methods. High water consumption, damage to compressor blades by water droplets, and inefficiency in humid climates are disadvantages of high-pressure fogging systems. Mechanical chillers have high electricity consumption and initial costs. In this research, an earth-to-air heat exchanger (EAHE) is introduced as a new method for inlet air cooling of gas turbines and is technically and economically compared with the two common methods in the long term in the climate of Tehran city. Temperature distribution in the ground is...

Planing Hull Longitudinal Motion Simulation

, M.Sc. Thesis Sharif University of Technology Seif, Tayyebe (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

Planing crafts in waves are characterized by large and violent vertical motion and acceleration. The hull structure is subjected to high impact loads and the crew experiences high transient vertical acceleration and in most cases the crew needs to lower speed in order to avoid damage to the hull.In recent years, interest on increasingly faster marine vehicles has remarkably grown. Typical planing monohulls are: patrol vessels, pilot boats, rescue vessels, coast guard vessels and small navy vessels. So the behavior of planing monohulls in waves has been a widely researched topic since more and more planing monohulls appeared.The accurate prediction of large amplitude ship motions in severe...

Review of Thermalization in Closed Quantum Systems

, M.Sc. Thesis Sharif University of Technology Seif, Negar (Author) ; Rezakhani, Ali (Supervisor)

Abstract

For a physical system, equilibrium is defined as a state in which the values of macroscopic quantities describing the system do not change in time. We observe systems around us reaching equilibrium every day. Describing such a seemingly simple phenomena has remained as one of the important challenges in theoretical physics. So far, various explanations for thermalization (approach to equilibrium) have been offered within classical and quantum thermodynamics. In classical statistical mechanics, the microcanonical ensemble provides a suitable prediction of the thermal behavior of a closed system. In this ensemble, using ergodic hypothesis and chaos theory one can assume that all microstates...

Experimental and numerical investigation of hydrodynamic performance of a new surface piercing propeller family

, Article Ocean Engineering ; Volume 264 , 2022 ; 00298018 (ISSN) Seif, M. S ; Teimouri, M ; Sharif University of Technology

Elsevier Ltd 2022

Abstract

Today, passenger and racing boats increasingly utilize surface-piercing propellers. This type of propeller operates in two distinct phases of water and air simultaneously. As a result, this propeller type has additional characteristics that must be investigated separately from conventional propellers. A new family of surface piercing propellers was investigated using experimental and numerical methods. The family consisted of five propeller models with varying geometric features operating at an immersion ratio of 0.7. Experiments were conducted in the Sharif University of Technology's hydrodynamic group's cavitation tunnel. Additionally, using Star-CCM + software, the numerical simulation...

Performance comparision between planing monohull and catamaran at high froude numbers

, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 28, Issue 4 B , 2004 , Pages 435-441 ; 03601307 (ISSN) Seif, M. S ; Amini, E ; Sharif University of Technology

2004

Abstract

Conventional ships have been used for many years with usual body forms. But recent developments in high speed crafts have created many different alternatives. Therefore the selection of hull type becomes an important issue in the preliminary design stage. This selection should be based on performance comparisons and also other parameters such as building costs. Since planing monohulls and catamarans are very popular types of high speed crafts, in this paper their behaviors from resistance at high speeds are compared. The results may prove useful for designers at conceptual or preliminary design stages. © Shiraz University

The study on the scaling effects in the surface piercing propeller

, Article Ocean Engineering ; Volume 267 , 2023 ; 00298018 (ISSN) Seif, M. S ; Teimouri, M ; Sharif University of Technology

Elsevier Ltd 2023

Abstract

Surface Piercing Propellers (SPPs) are widely used in high-speed crafts. These types of propellers can work at high rotational speeds and in a turbulent environment with high efficiency. One of the most widely used methods in estimating the performance of conventional marine propellers is the use of model testing in towing tank or cavitation tunnel. These propellers' open water hydrodynamic performance can be checked in a laboratory test before being made at full scale. According to the lack of similarity between the model and the full scale in this type of propeller, the flow regime is not the same as the scale values of the model, which leads to the difference in the hydrodynamic...

Drag force on a flat plate in cavitating flows

, Article Polish Maritime Research ; Volume 16, Issue 3 , 2009 , Pages 18-25 ; 12332585 (ISSN) Seif, M ; Asnaghi, A ; Jahanbakhsh, E ; Sharif University of Technology

2009

Abstract

The present study focuses on the simulation of two dimensional unsteady cavitating flows. For simulation of unsteady behaviors of cavitation which have practical applications, the development of unsteady PISO algorithm based on the non-conservative approach is utilized. For multi-phase simulation, single-fluid Navier-Stokes equations, along with the volume fraction transport equation, are employed. The bubble dynamics model is utilized to simulate phase change between vapor and liquid phases of the water. Unsteady simulation of cavitation around NACA66(MOD) and supercavitation around a flat plate normal to flow direction are performed to clarify accuracy of presented model. Numerical results...

A practical method for aerodynamic investigation of WIG

, Article Aircraft Engineering and Aerospace Technology ; Volume 88, Issue 1 , 2016 , Pages 73-81 ; 00022667 (ISSN) Seif, M. S ; Tavakoli Dakhrabadi, M ; Sharif University of Technology

Emerald Group Publishing Ltd 2016

Abstract

Purpose - The purpose of this paper is to present a fast, economical and practical method for mathematical modeling of aerodynamic characteristics of rectangular wing in ground (WIG) effect. Design/methodology/approach - Reynolds averaged Navier-Stokes (RANS) equations were converted to Bernoulli equation by reasonable assumptions. Also, Helmbold's equation has been developed for calculation of the slope of wing lift coefficient in ground effect by defining equivalent aspect ratio (ARe). Comparison of present work results against the experimental results has shown good agreement. Findings - A practical mathematical modeling with lower computational time and higher accuracy was presented for...

Study of Drag Reduction of Ship by Different Coating and Paint

, M.Sc. Thesis Sharif University of Technology Kianejad, Sadroddin (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

Reduction ships resistance is the major issues that always been about moving the ship into a water. In the course of research, many scientists have been interest to resistance reduction. It is important protect the body of ship against damage caused by sticking marine algae and crustaceans as protection against corrosive agents. Marine organisms such as algae, crustaceans and bacteria stick on submerged surfaces and increase the ship resistance. In this thesis resistance reduction using coating is evaluated. Foul release paint make smooth surface and low surface energy therefore ship with foul release coating experience lower drag contrast ship with another coating in the unfouled condition....

Simulation of Wave Propagation in the Sea

, M.Sc. Thesis Sharif University of Technology Taheri, Masoud (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

In positioning and navigation, Sonar with utilization of sound waves in water environments is similar to the role of Radar in not watered (irrigated) environments. In the Sonar field, modeling and simulation of propagation of sound waves in the undersea environment is a fundamental and very important topic. Nowadays simulation is significant tool that allow to the researchers to predict the quality of Sonar function respect to the experimental conditions. For simulation and modeling of sound wave propagation are used two different methods; Wave theory and Ray theory. In the wave theory, because of the large volume of data, the interpretation of the results is hard. Also in this method cannot...

Design and Construction of Autonomous Underwater Vehicles

, M.Sc. Thesis Sharif University of Technology Spehrband, Poria (Author) ; Seif, Mohammad Saeid (Supervisor)

Abstract

In recent years, unmanned vehicles have intensively been developed to reduce human dangers for marine applications. Predicting the hydrodynamic coefficients of an autonomous underwater vehicle is important during the vehicle’s design phase. In other words to design an AUV, one must clarify its maneuverability and controllability based on a mathematical model. The mathematical model contains various hydrodynamic forces and moments expressed collectively in terms of hydrodynamic coefficients. Therefore, the correct values of the coefficients must be known to precisely design the controller of AUVs.SUT-2 is an AUV, being developed by Marine Engineering Laboratory of Sharif University of...

Numerical Modeling of Unsteady Partial Cavitaion over Axisymmetric Bodies Using Boundary Element Method

, M.Sc. Thesis Sharif University of Technology Emami, Pedram (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

In this thesis, the potential flow including unsteady partial cavitation around axisymmetric bodies are studied using a boundary element method (BEM) based on potential theory. For this purpose the wetted surface of the body and cavity surface are divided (approximated) to panels. Then, by applying the Green’s third identity and expressing this theory in potential flow around every surface, cavitation can be modeled by distributing the source and the dipole rings on cavity/body surface. In order to approaching this goal we introduced dipole rings distribution on the cavity and body surfaces and source rings distribution on the cavity surface. In this work the cavitation number is assumed to...

Numerical Modeling and Analyzing of Pumpjet Propulsion System

, M.Sc. Thesis Sharif University of Technology Bozorgi, Soheil (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

Nowadays, reaching higher speed in marine crafts and underwater vehicles mostly requires a modern propulsor with high efficiency and enhanced cavitation performance. Because of these requirements, numerous researches for developing the existing propulsion systems and invention of new systems have been conducted in recent years. One of the most sophisticated and developed propulsion systems that have high hydrodynamic efficiency and high cavitation performance and low acoustic signature is pumpjet. This propulsor contains a rotor, stator and a duct that surrounds two other parts. Stator reduces the swirl of flow coming from rotor and thereby reduces the loss of energy. High cavitation...

The Effect of Control Surfaces on Longitudinal Motions of High Speed Catamaran Vessels

, Ph.D. Dissertation Sharif University of Technology Najafi, Amin (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

The purpose of this study is extracting a dynamic model of longitudinal motions of high speed catamaran in regular and irregular waves, and then motion control of vessels by using of foil control elements and interceptor. For simulating longitudinal motions in regular waves, at first the longitudinal hydrodynamic coefficients of vessels should be extracted, then by substituting extracted coefficients in cumminz equation and using system identification methods, some equations are presented to estimate longitudinal two degree of freedom motions of high speed catamaran in waves. In this thesis the extraction of hydrodynamic coefficients is based on both numerical and experimental methods. ANSYS...

Rudder and Propeller Interaction Analysis in Planing Craft

, M.Sc. Thesis Sharif University of Technology Taheri, Mohammad (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

Partially submerged propellers are new type of propellers which knowledges ragard them is limited. These propellers found a growing market ahead of them and expertsexpect to use these propellers for big vessels at high speeds. This type of propulsors do not lose their efficiences at high speeds and are assumped to be economical. Meanwhile due to continuosus hit to water surface, huge stresses are extered on tha blade witch needs to be fundamentally studied. Several researchers have studied the partially submerged propellers which unfortunately did not publish their results. Undergo less or more thrust and torques which in both cases the efficiency also increases. The use of numerical methods...

Modeling the Effects of Step and Spray Rails on Planing Hulls Hydrodynamics

, M.Sc. Thesis Sharif University of Technology Aqajani, Alireza (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

High speed crafts due to their design, geometry, one of the parameters to improve the performance of hydrodynamic elements such as trim tabs, bow thruster, steps and Spray rails.Step is an element which change height of bottom and due to reduce wetted area and extra lift and finally cause to improve drag of vessel.In this thesis we have evaluated numerically and compared with experimental tests on planning crafts in calm water and waves, and the effects on the motions of floating and drag floating are compared.Numerical analysis is conducted to help Ansys.CFX software. First, to provide 2D modeling and analyzing real-bodies floating in calm water and waves with simple, step-paid. The...

Hydroelastic Analysis of Surface Piercing Propeller

, M.Sc. Thesis Sharif University of Technology Fatemeh, Shahreki (Author) ; Seif, Mohamad Saeed (Supervisor)

Abstract

Surface piercing propellers are particular type of supercavitating propellers that are commonly used for High-speed vessels. Most studies on this type of propellers has been investigating the hydrodynamic forces. But in recent years with increase in SPPs diameter used in vessels, structural analysis of this type of propellers is considered. For this purpose, studies on the stresses exerted on the propeller structures under load is done with the help of Hydro elastic methods. In this type of analysis, structura of propeller is intended to be flexible and Displacements under pressure checked and Tensions resulting from it are studied.
The present Thesis using ANSYS software to analyze a...

Numerical Simulation of Cavitation in Rigid Body Motion in Unsteady State

, M.Sc. Thesis Sharif University of Technology Asnaghi, Abolfazl (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

In this thesis, cavitating flow over 2D/3D geometries of cavitators and projectile bodies in stationary and moving conditions are simulated using the "Volume of Fluid" (VOF) technique. The main application of VOF model is for simulating free surface flows. In this work, another capability is added to the VOF algorithm to solve for gas phase and by applying analytical-numerical mass transfer models, cavitation phenomenon is simulated. The developed algorithm precisely simulates the geometrical parameters of supercavities such as dimension and shape in a wide range of cavitation numbers. In addition, the flow parameters of supercavity such as drag coefficient, pressure coefficient inside the...