M. Shafiey Dehaj; R. Ebrahimi; H. Karimi; A. Jalali; M. Naderi
Volume 6, Issue 4 , January 2014, , Pages 1-11
Abstract
The effects of liquid propellant rocket engines thrust termination transients are important in achieving the launch vehicle’s desired final velocity with the required precision. In this paper, a mathematical model has been developed to predict the changes in the combustion chamber pressure and ...
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The effects of liquid propellant rocket engines thrust termination transients are important in achieving the launch vehicle’s desired final velocity with the required precision. In this paper, a mathematical model has been developed to predict the changes in the combustion chamber pressure and the related cut-off impulse based on the physical aspects of engine’s components. The modeling is divided into four steps: (1) from issuing the cut-off command to the activation of valve (2) from the time of executing the stop command until the end of the operation of the cut-off valves, (3)from the time that after the valve is shutt closed until the combustion chamber is extinguished and (4) simulation of the phase change and propellant components evaporation in corrugates. Results suggest that the duration of the first two steps have a significant effect on increasing or decreasing the amount of the thrust force and the 4th step’s thrust is less than 10 percent of nominal value while, the most thrust fluctuations appear in this step.
M. Mirshams; H. Karimi; H. Naseh
Volume 1, Issue 2 , December 2008, , Pages 17-25
Abstract
The principle goal of this paper is to introduce Launch Vehicle Conceptual Design (LVCD) software based on multi-parameter optimization idea. The main objectives of this software arereduction of the cost and time of conceptual design phase. This software is user friendly such that an operator familiar ...
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The principle goal of this paper is to introduce Launch Vehicle Conceptual Design (LVCD) software based on multi-parameter optimization idea. The main objectives of this software arereduction of the cost and time of conceptual design phase. This software is user friendly such that an operator familiar with fundamentals of design and launch vehicle mass – energy equations and with primary training operator is capable to work with LVCD.The algorithm used in LVCD, is based on combinational optimization of major design parameters. To this end, ten sub-algorithms will be presented in this design approach. Mass distribution of different stages to launch maximum payload mass to the orbit, pitch program trajectory to get to the maximum final velocity, and providing minimum velocity loss due to gravity, and also minimum axial acceleration of various stages of launch vehicle will be optimized as the results of the presented approach. The optimization process is performed subject to the restrictions. Also, the performance index is optimized in a mutual iteration mechanism (multi-parameter optimization). Evaluation and verification of the presented method is performed using available data of two and three-stage launch vehicles.
M. Mirshams; H. Karimi; H. Naseh
Volume 1, Issue 1 , September 2008, , Pages 21-36
Abstract
The principle goal of this paper is developing of Launch Vehicle Conceptual Design (LVCD) method based on combinational optimization of major design parameters. To this end, ten sub-algorithms will be presented in this design approach. Mass distribution of different stages to launch maximum payload mass ...
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The principle goal of this paper is developing of Launch Vehicle Conceptual Design (LVCD) method based on combinational optimization of major design parameters. To this end, ten sub-algorithms will be presented in this design approach. Mass distribution of different stages to launch maximum payload mass to the orbit, pitch program trajectory to get to the maximum final velocity, and providing minimum velocity loss due to gravity, and also minimum axial acceleration of various stages of launch vehicle will be optimized as the results of the presented approach. The optimization process is performed subject to the restrictions. Also, the performance index is optimized in a mutual iteration mechanism. Evaluation and verification of the presented method is performed using available data of two and three-stage launch vehicles.
