Search for: computational-fluid-dynamics-simulations
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    Multi-objective trade-off analysis of an integrated cold gas propulsion system

    , Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 227, Issue 8 , 2013 , Pages 1233-1250 ; 09544100 (ISSN) Banazadeh, A ; Gol, H. A ; Sharif University of Technology
    The overall design of cold gas propulsion systems is pretty complicated when considering the mission requirements, operating constraints and functional limitations imposed by the mechanical components. To address this complication, a precise design process is proposed, which attempts to optimize the cost of operation as well as to minimize the waste volume and weight by using multi-objective trade-off analysis. This analysis is based on a set of ordinary differential equations that are solved iteratively to describe the optimal behavior of the system. Therefore, a numerical code is being developed to give insight on the design sensitivity with respect to uncertainties on the design... 

    Dynamics of drops - Formation, growth, oscillation, detachment, and coalescence

    , Article Advances in Colloid and Interface Science ; Volume 222 , 2015 , Pages 413-424 ; 00018686 (ISSN) Karbaschi, M ; Taeibi Rahni, M ; Javadi, A ; Cronan, C. L ; Schano, K. H ; Faraji, S ; Won, J. Y ; Ferri, J. K ; Krägel, J ; Miller, R ; Sharif University of Technology
    Elsevier  2015
    Single drops or bubbles are frequently used for the characterization of liquid- fluid interfaces. Their advantage is the small volume and the various protocols of their formation. Thus, several important methods are based on single drops and bubbles, such as capillary pressure and profile analysis tensiometry. However, these methods are often applied under dynamic conditions, although their principles are defined under equilibrium conditions. Thus, specific attention has to be paid when these methods are used beyond certain limits. In many cases, computational fluid dynamics (CFD) simulations have allowed researchers, to extend these limits and to gain important information on the... 

    Experimental analysis of a Ranque-Hilsch vortex tube for optimizing nozzle numbers and diameter

    , Article Applied Thermal Engineering ; Volume 61, Issue 2 , 2013 , Pages 500-506 ; 13594311 (ISSN) Mohammadi, S ; Farhadi, F ; Sharif University of Technology
    A brass vortex tube with changeable parts is used to obtain the optimum nozzle intake numbers and diameter. The effects of inlet pressure and CF (cold fraction) are also investigated. Results illustrate that increasing the number of nozzles causes a temperature drop and the optimum nozzle diameter corresponds to quarter of vortex tube diameter. The distance between cold end orifice and nozzle intakes is investigated in this work and it is found that for a better performance, this distance should be decreased. A series of experiments conducted to investigate the CF effect on VT performance and an optimum amount for this parameter is found. A two-dimensional computational fluid dynamics... 

    Numerical study of aero- acoustic characteristics in an automotive air-intake system

    , Article 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013: Noise Control for Quality of Life ; Volume 7 , 2013 , Pages 5990-5999 ; 9781632662675 (ISBN) Jahani, K ; Beigmoradi, S ; Sharif University of Technology
    OAL-Osterreichischer Arbeitsring fur Larmbekampfung  2013
    Compartment noise has gained significant importance to meet customer expectation. One of the dominant sources of noise from whole engine as a system is the one which is induced from fresh air intake. Geometrical features in air induction systems (AIS) airflow path are often responsible for unusual noise due to the complex air flow structure and its interaction with the internal acoustic field. To reduce air intake noise basically resonator and expansion chamber are used on automotive vehicles. Resonators are widely used for noise reduction of air induction systems. Although, airflow bench tests are faster to evaluate various alternate design geometries, understanding the mechanism of such... 

    Multi-objective optimization of lean and sweep angles for stator and rotor blades of an axial turbine

    , Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 229, Issue 5 , June , 2015 , Pages 906-916 ; 09544100 (ISSN) Asgarshamsi, A ; Benisi, A. H ; Assempour, A ; Pourfarzaneh, H ; Sharif University of Technology
    SAGE Publications Ltd  2015
    The axial turbine is one of the most challenging components of gas turbines for industrial and aerospace applications. With the ever-increasing requirement for high-aerodynamic performance blades, three-dimensional aerodynamic shape optimization is of great importance. In this research, the rear part of a gas turbine consisting of a one-stage axial turbine is optimized numerically. A useful optimization algorithm is presented to improve the efficiency and/or pressure ratio of the axial turbine with two different objective functions. The three-dimensional blade-shape optimization is employed to study the effects of the turbine stator and rotor lean and sweep angles on the turbine performance.... 

    Prediction of downhole flow regimes in deviated horizontal wells for production log interpretation

    , Article Society of Petroleum Engineers - Trinidad and Tobago Energy Resources Conference 2010, SPE TT 2010, 27 June 2010 through 30 June 2010 ; Volume 2 , June , 2010 , Pages 525-530 ; 9781617388859 (ISBN) Bahrami, H ; Hosseinian, A ; Rasouli, V ; Siavoshi, J ; Mirabolghasemi, M ; Sinanan, B ; Bagherian, B ; Sharif University of Technology
    Production logging is used to evaluate wells production performance. Interpretation of production log data provides velocity profile and contribution of each zone on total production. In multi-phase flow conditions, production log interpretation can be challenging since producing fluids do not have similar densities and travel with different speed depending on fluids properties and wellbore deviation. Production log interpretation in multi-phase producing wells requires identifying downhole flow regimes and determining velocity profile for each phase. There are different flow regimes and velocity models available, which are being used in production log interpretation to determine wells flow... 

    CFD modeling of immiscible liquids turbulent dispersion in Kenics static mixers: Focusing on droplet behavior

    , Article Chinese Journal of Chemical Engineering ; Volume 28, Issue 2 , 2020 , Pages 348-361 Haddadi, M. M ; Hosseini, S. H ; Rashtchian, D ; Ahmadi, G ; Sharif University of Technology
    Chemical Industry Press  2020
    The present study is concerned with the computational fluid dynamics (CFD) simulation of turbulent dispersion of immiscible liquids, namely, water–silicone oil and water–benzene through Kenics static mixers using the Eulerian–Eulerian and Eulerian–Lagrangian approaches of the ANSYS Fluent 16.0 software. To study the droplet size distribution (DSD), the Eulerian formulation incorporating a population balance model (PBM) was employed. For the Eulerian–Lagrangian approach, a discrete phase model (DPM) in conjunction with the Eulerian approach for continuous phase simulation was used to predict the residence time distribution (RTD) of droplets. In both approaches, a shear stress transport (SST)... 

    Impact of oil polarity on the mixing time at the pore scale in low salinity waterflooding

    , Article Energy and Fuels ; Volume 34, Issue 10 , 16 September , 2020 , Pages 12247-12259 Mohammadi, S ; Mahani, H ; Ayatollahi, S ; Niasar, V ; Sharif University of Technology
    American Chemical Society  2020
    The efficiency of low salinity waterflooding, particularly during tertiary mode injection, is highly controlled by in situ mixing between the stagnant regions holding high salinity water (HSW) and the flowing regions containing low salinity water (LSW) because it impacts directly the electrokinetics of wettability alteration and the time scale of the low salinity effect. This study aims to address the effects of oil polarity and charged rock surfaces on the time scale of mixing and transport under two-phase flow conditions. A systematic series of micromodel experiments were performed. The micromodels were first saturated with high salinity formation brine and oil (both model and crude oil);... 

    Producing water from saline streams using membrane distillation: Modeling and optimization using CFD and design expert

    , Article International Journal of Energy Research ; Volume 44, Issue 11 , 2020 , Pages 8841-8853 Shokrollahi, M ; Rezakazemi, M ; Younas, M ; Sharif University of Technology
    John Wiley and Sons Ltd  2020
    Due to the increasing need for drinking water in the world, various membrane processes have been developing significantly over the past several years. The process of membrane distillation is one of the non-isothermal processes that cause steam to pass from the membrane due to the difference in temperature and the resulting difference in vapor pressure. Due to the lack of precision in the amount of flux and thermal efficiency in various operating conditions the membrane distillation process still needs development. This article attempted to examine the effects of flowrate, temperature, and module length on the performance of the membrane distillation process using computational fluid dynamics...