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Experimental and Theoretical Investigation of Mixture Formation in CNG Direct Injection of Spark Ignition
, Ph.D. Dissertation Sharif University of Technology ; Saidi, Mohammad Hasan (Supervisor) ; Mozafari, Ali Asghar (Supervisor)
Abstract
Due to increasing of internal combustion engine applications in metropolitan, reduction of emission is one of the challenging issues for engine companies. Natural gas is a promising fuel for the strict legislation of emission in many countries. Vast variety of natural gas sources in Iran and also lower carbon to hydrogen content of natural gas motivates us to use this fuel for engine application. Using natural gas also helps to increase the variety of fuel basket in Iran. Present research has focused on mixture formation and injection characteristics of natural gas direct injection engine. Injection and mixture formation in direct injection engines is very important for good combustion and...
Analytical and Numerical Investigation of Fuel Spray Characteristics in a Direct Injection Engine
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor)
Abstract
With the increasing number of applications in internal combustion engines, environmental impact and air pollution caused by emissions has been much attention. Natural gas is a promising fuel for limiting pollution laws in many countries. The use of fuel with a higher ratio of hydrogen gas to carbon pollution reduction motor. In this context and with regard to development policy and also due to the diversity basket NGV fuel, fuel injection, has been modeled analytically and numerically in a direct injection engine. In this study, an analytical model for spray injection fuel delivery and is dissolved. The resolution of the method of separation of variables is taken. The effect of the nozzle...
Semi analytical solution to transient start of weakly underexpanded turbulent jet
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 133, Issue 9 , Sep , 2011 ; 00982202 (ISSN) ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
2011
Abstract
This study presents a semi analytical solution for the transient weakly underexpanded jet. Different polytropic processes are compared with available experimental data in the literature to assess the best process for steady and transient weakly underexpanded jets. The steady state results agree reasonably well with the experimental and analytical data. It is also shown that isentropic process evaluates steady injection better than other processes. Tip penetration of transient results was compared with available data in literature, and no exact agreement for isothermal and isentropic is observed. This appears due to the linearization of equation of state. It is suggested that more accurate...
Experimental and numerical investigation on the jet characteristics of spark ignition direct injection gaseous injector
, Article Applied Energy ; Volume 105 , 2013 , Pages 8-16 ; 03062619 (ISSN) ; Saidi, M. H ; Mozafari, A. A ; Hajialimohammadi, A ; Sharif University of Technology
2013
Abstract
Natural gas has widely been used as a fuel in conventional Diesel and spark ignition engines. The better understanding of injector parameters on the jet structure is helpful for the combustion optimization. This paper presents an experimental and numerical study on the jet structure of gaseous fuel injector in spark ignition direct injection engine by Schlieren technique and numerical procedure. Helium was injected through a gaseous injector at the different pressure ratios and nozzle diameters to understand the effects of nozzle geometry and pressure ratio for a dedicated correlation of CNG-SIDI injector. It was found that higher pressure ratio and exit nozzle diameter led to more tip...