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Modeling and Investigation of Complexities Induced by Constant Volume Combustion Frequencies in a Gas Turbine Engine
, M.Sc. Thesis Sharif University of Technology ; Ghorbanian, Kaveh (Supervisor)
Abstract
The objective of this research is to investigate the basic design challenges of a first stage turbine nozzle in a constant volume combustion (CVC) gas turbine engine. In general, CVC cycles have higher thermal efficiency and specific power despite their unstable combustion phenomenon which is due to moving as well as oscillating shock waves with a specific frequency and amplitude and resulting in a challenge to the engine designer. In this thesis, first, the performance parameters of CPC and CVC cycles are introduced and compared. Further, a model is developed to examine the flow non-uniformity, entropy generation, cycle thermal efficiency, and specific fuel consumption of a flow through the...
Effect of Initial Static Shear Stress on Liquefaction Resistance of Babolsar Sand Using Cyclic Simple Shear Tests
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
Initial static shear stress caused by slopes or nearby structures' foundations can affect the behavior of the soil which is concerned many investigators during previous three decade. In this investigation, the effect of initial static shear stress on the liquefaction resistance of Babolsar sand has been probed using cyclic simple shear tests. Three different initial relative densities (Dr0=20%, 40% and 60%) and three different initial normal stresses (σv0= 50, 150 and 250 kPa) were considered in tests and four various initial static shear ratios (α) ranging between 0.0 and 0.3 were applied which leads to more than 190 distinct experiments. All tests were conducted under constant volume and...
Design and manufacturing of a constant volume test combustion chamber for jet and flame visualization of CNG direct injection
, Article Applied Mechanics and Materials ; Volume 217-219 , 2012 , Pages 2539-2545 ; 16609336 (ISSN) ; 9783037855027 (ISBN) ; Ahmadisoleymani, S. S ; Abdullah, A ; Asgari, O ; Rezai, F
2012
Abstract
Constant volume transparent test combustion chambers are extensively used for investigating injection and fuel burning properties of various combustion engines. Their configuration depends on the engine type and the research purpose. Material of components, shape and dimensions of the chamber and its parts, ease of use, accessibility, sealing and safety of the assembly are the parameters needed to be considered in designing the test cell. This paper explains, structural design of a test combustion chamber and its optical windows using finite element analysis of ANSYS 12.0 software for bearing high pressure variations and thermal shocks of combustion. It was designed for conducting CNG direct...
Numerical Investigation of the Turbine Nozzle Performance due to Pulsating Flow of a Constant Volume Combustion Gas Turbine Engine
, M.Sc. Thesis Sharif University of Technology ; Ghorbanian, Kaveh (Supervisor)
Abstract
In present research, Numerical investigation of the turbine nozzle performance due to pulsating flow of a constant volume combustion gas turbine engine has been done. For this purpose, first the blade row is modeled with the BladeGen tool of ANSYS software and then, using the TurboGrid tool, a structured three-dimensional grid is generated and simulated by the ANSYS CFX solver. After simulation, numerical solution validation was performed using the available data. In the last step, after ensuring the boundary conditions and numerical solution methods, the effect of different parameters on the performance of the turbine nozzle is investigated. Finally, to observe the effect of geometric...
Development of a new workflow for pseudo-component generation of reservoir fluid detailed analysis: A gas condensate case study
, Article International Journal of Oil, Gas and Coal Technology ; Vol. 7, Issue. 3 , 2014 , pp. 275-297 ; ISSN: 1753-3317 ; Pishvaie, M. R ; Ghotbi, C ; Mittermeir, G. M ; Sharif University of Technology
Abstract
In this work, a new automatic workflow for accurate optimal pseudo-component generation from gas condensate mixtures with a large number of components is presented. This workflow has a good insight into thermo-physical and critical properties and introduces only a small amount of loss of information and EOS flexibility. In this regard, the fuzzy clustering is used to classify the components in the mixture based on the similarities in the critical properties. The mixing rules are then applied to find group properties. Two different approaches for components association in clustering process are investigated with several numbers of groups. The mathematical validity of the groups is controlled...
Lean partially premixed combustion investigation of methane direct-injection under different characteristic parameters
, Article Journal of Energy Resources Technology, Transactions of the ASME ; Vol. 136, issue. 2 , 2014 ; ISSN: 01950738 ; Metghalchi, H ; Hannani, S. K ; Hemmati, H ; Ebrahimi, R ; Sharif University of Technology
Abstract
The effects of hydrogen addition, diluent addition, injection pressure, chamber pressure, chamber temperature and turbulence intensity on methane-air partially premixed turbulent combustion have been studied experimentally using a constant volume combustion chamber (CVCC). The fuel-air mixture was ignited by centrally located electrodes at given spark delay times of 1, 5, 40, 75, and 110 ms. Experiments were performed for a wide range of hydrogen volumetric fractions (0% to 40%), simulated diluent volumetric fractions (0% to 25% as a diluent), injection pressures (30-90 bar), chamber pressures (1-3 bar), chamber temperatures (298-432 K) and overall equivalence ratios of 0.6, 0.8, and 1.0....
Challenges of fluid phase behavior modeling in Iranian retrograde gas condensate reservoirs
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 37, Issue 6 , Feb , 2015 , Pages 663-669 ; 15567036 (ISSN) ; Asadi, E ; Nasiri, M ; Khajenoori, L ; Masihi, M ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
Production from gas condensate reservoirs requires precise determination of reservoir fluid properties along with their positive impact on real reservoir performance evaluation and fluid in place volume calculation. This fact is particularly important because liquid drop out phenomena occurs as a result of pressure drop due to fluid production and condensate remains in reservoir [Mohebzadeh, 2005. In this study the challenges and problems of fluid phase behavior simulation in southern Iranian retrograde gas condensate reservoirs is discussed. Most of the problems and challenges are inaccuracy of equation of states near the critical point, special conditions and produced fluid flow...
Fundamental study of spray and partially premixed combustion of methane/air mixture
, Article ASME 2012 Internal Combustion Engine Division Fall Technical Conference, ICEF 2012 ; 2012 , Pages 417-426 ; 9780791855096 (ISBN) ; Metghalchi, H ; Moghaddas, A ; Hannani, S. K ; Ebrahimi, R ; Sharif University of Technology
2012
Abstract
This study presents fundamentals of spray and partially premixed combustion characteristics of directly injected methane inside a constant volume combustion chamber (CVCC). The constant volume vessel is a cylinder with inside diameter of 135 mm and inside height of 135 mm. Two end of the vessel are equipped with optical windows. A high speed complementary metal oxide semiconductor (CMOS) camera capable of capturing pictures up to 40, 000 frames per second is used to observe flow conditions inside the chamber. The injected fuel jet generates turbulence in the vessel and forms a turbulent heterogeneous fuel-air mixture in the vessel, similar to that in a compressed natural gas (CNG) direct...
A new multi-sample EOS model for the gas condensate phase behavior analysis
, Article Oil and Gas Science and Technology ; Volume 66, Issue 6 , September , 2011 , Pages 1025-1033 ; 12944475 (ISSN) ; Crespo, F ; Sharif University of Technology
2011
Abstract
Equations of State EOS are vastly being used to predict the phase behavior of reservoir fluids. The accuracy of EOS modeling technique over conventional correlation models would benefit an improved property prediction of these fluids. Once the crude oil or gas condensate fluid system has been probably characterized using limited laboratory tests, its PVT behavior under a variety of conditions can be easily studied. In this paper, the PVT behavior of gas condensate from a reservoir in South Pars retrograde gas field in Iran was modeled using the three-parameter Patel and Teja Equation of State. The multi-sample characterization method is used to arrive at one consistent model for retrograde...