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Experimental Study of Acceleration Effect on Combustion Chamber Pressure Field
, M.Sc. Thesis Sharif University of Technology ; Farahani, Mohammad (Supervisor) ; Mohammadi, Alireza (Co-Supervisor)
Abstract
This thesis is conducted to study acceleration effect on the burning rate augmentation of a solid propellant. A centrifugal experimental setup is designed to obtain a uniform acceleration field. An internal burning tube is used as grain, so acceleration vector is always perpendicular to burning surface of propellant. Inner radius of tube is small, so the magnitude of acceleration increases as the grain burns back. The pressure of combustion chamber was changed from 30 bar to 80 bar by changing the nozzle throat and the magnitude of acceleration changed from 2g to 60g by changing the rotational speed of SRM. Burning time of all tests was below 2 sec. due to small web of the grain. Pressure of...
SRM performance improvement: Erosive burning phenomenon
, Article AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference, Sacramento, CA, 9 July 2006 through 12 July 2006 ; Volume 10 , 2006 , Pages 7649-7653 ; 1563478188 (ISBN); 9781563478185 (ISBN) ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2006
Abstract
In this paper, the internal ballistics of solid propellant rocket motor with an arbitrary grain configuration is numerically investigated using quasi one dimensional simulation of Inviscid conservation equations. The upwind Roe's scheme is used to calculate the convective fluxes. Appropriate burning rate model to predict the erosive burning in solid propellant is used here. By using this phenomenon and accurate simulation, tactical motor performance can be considerably improved
Effect of Air by Oxygen Enrichmenton Burning Rate of Polyethylen in Vortex Ramjet
, M.Sc. Thesis Sharif University of Technology ; Ghafoorian, Akbar (Supervisor) ; Ghorbanian, Kaveh (Supervisor) ; Saeedi, Mohammad Hassan (Co-Advisor) ; Mozaffari, Ali Asghar (Co-Advisor)
Abstract
Bidirectional axial vortex flow and air enriched with oxygen are used in order to increase solid fuel burning rate in both subsonic and supersonic ramjet engines experimentally. Vortex flow enhances combustion by causing erosive burning on the surface of the solid fuel. Air enriched by oxygen increases the combustion temperature. Therefore, they make the usage of subsonic ramjet engines possible for applications in which a low thrust is need for a long duration. An experimental ramjet engine with the capability of simulating subsonic and supersonic flight conditions was designed and fabricated. Polyethylene and oxygen enriched air are used as solid fuel and oxidizer respectively. ...
Experimental study of fuel regression rate in an HTPB/N2O hybrid rocket motor
, Article Scientia Iranica ; Volume 25, Issue 1 , 2018 , Pages 253-265 ; 10263098 (ISSN) ; Soltani, M. R ; Mohammadi, A. R ; Sharif University of Technology
Sharif University of Technology
2018
Abstract
The performance of an HTPB/N2O hybrid motor was experimentally investigated. A hybrid motor was designed and manufactured in a laboratory with the purpose of studying the effects of various parameters on the motor's performance, including fuel regression rate and specific impulse. A series of tests were conducted to find a correlation between the fuel regression rate and the oxidizer's mass flux. The effects of chamber's pressure on the regression rate as well as other performance parameters were investigated. While the burning rate did not change dramatically, both the efficiency and ISP of the motor increased. The local fuel regression rate and the fuel port were also calculated. In...
Improvement and experimental validation of a multi-zone model for combustion and NO emissions in CNG fueled spark ignition engine
, Article Journal of Mechanical Science and Technology ; Volume 26, Issue 4 , 2012 , Pages 1205-1212 ; 1738494X (ISSN) ; Hannani, S. K ; Ebrahimi, R ; Sharif University of Technology
2012
Abstract
This article reports the experimental and theoretical results for a spark ignition engine working with compressed natural gas as a fuel. The theoretical part of this work uses a zero-dimensional, multi-zone combustion model in order to predict nitric oxide (NO) emission in a spark ignition (SI) engine. The basic concept of the model is the division of the burned gas into several distinct zones for taking into account the temperature stratification of the burned mixture during combustion. This is especially important for accurate NO emissions predictions, since NO formation is strongly temperature dependent. During combustion, 12 products are obtained by chemical equilibrium via Gibbs energy...
Theoretical and experimental modeling of vortex engine in ramjet application
, Article 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 2 August 2009 through 5 August 2009, Denver, CO ; 2009 ; 9781563479762 (ISBN) ; Ghafourian, A ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
Abstract
A new experimental facility was designed, fabricated and tested to model and study the possibility of applying the bidirectional swirl flow on the combustion chamber of airbreathing subsonic ramjet engine. Appropriate intake was designed to convert axial external air to tangential swirl flow inside the combustion chamber. Inlets with appropriate angles conduct the swirl flow into the chamber and create bidirectional swirl flow field in the combustion chamber. This flow field has been modeled theoretically to determine the velocity field characteristics by previous researchers. Bidirectional swirl flow in liquid fuel ramjet engines has the proven advantage of keeping the combustion chamber...
Thermodynamic model for prediction of performance and emission characteristics of SI engine fuelled by gasoline and natural gas with experimental verification
, Article Journal of Mechanical Science and Technology ; Volume 26, Issue 7 , July , 2012 , Pages 2213-2225 ; 1738494X (ISSN) ; Asghar, H. A ; Asghar, M. A ; Sharif University of Technology
2012
Abstract
In this study, a thermodynamic cycle simulation of a conventional four-stroke SI engine has been carried out to predict the engine performance and emissions. The first law of thermodynamics has been applied to determine in-cylinder temperature and pressure as a function of crank angle. The Newton-Raphson method was used for the numerical solution of the equations. The non-differential form of equations resulted in the simplicity and ease of the solution to predict the engine performance. Two-zone model for the combustion process simulation has been used and the mass burning rate was predicted by simulating spherical propagation of the flame front. Also, temperature dependence of specific...
A comparative study of the performance of a SI engine fuelled by natural gas as alternative fuel by thermodynamic simulation
, Article 2009 ASME Internal Combustion Engine Division Fall Technical Conference, ICEF 2009, Lucerne, 27 September 2009 through 30 September 2009 ; 2009 , Pages 49-57 ; 9780791843635 (ISBN) ; Hamidi, A. A ; Mozafari, A. A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2009
Abstract
With the declining energy resources and increase of pollutant emissions, a great deal of efforts has been focused on the development of alternatives for fossil fuels. One of the promising alternative fuels to gasoline in the internal combustion engine is natural gas [1-5]. The application of natural gas in current internal combustion engines is realistic due to its many benefits. The higher thermal efficiency due to the higher octane value and lower exhaust emissions including CO2 as a result of the lower carbon to hydrogen ratio of the fuel are the two important feature of using CNG as an alternative fuel. It is well known that computer simulation codes are valuable economically as a cost...