Hadiseh Karimaei
Volume 12, Issue 2 , September 2019, , Pages 11-21
Abstract
the effect of the internal geometry of the injector of a low-thrust monopropellant thruster on the characteristics of the outlet liquid sheet, such as the liquid sheet thickness, the spray cone angle, the average output velocity, and its mass flow rate, have been studied. For this purpose, simulation ...
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the effect of the internal geometry of the injector of a low-thrust monopropellant thruster on the characteristics of the outlet liquid sheet, such as the liquid sheet thickness, the spray cone angle, the average output velocity, and its mass flow rate, have been studied. For this purpose, simulation of the internal flow based on the computational fluid dynamics was performed to predict the output flow characteristics, then parametric studies were conducted to investigate the effect of geometry. In order to extract a predictive model for the preliminary design of the injector, a neural fuzzy network model was used. Using this model, the results of parametric analyzes were used to obtain a geometric specification without geometric modeling and computational fluid dynamics analysis or the use of initial design methods. The purpose of the implementation of the neural network model is to obtain an estimate of the internal geometry of the injector by entering the desired macroscopic characteristics of the output flow.
Hadiseh Karimaei; Mohammad Reza Salimi; Hassan Naseh; Ehsan Jokari
Volume 12, Issue 1 , April 2019, , Pages 13-22
Abstract
In this paper, design and physical configuration of various components of a 10N Monopropellant Hydrazine Thruster focusing on design calculations and optimization of catalytic combustion chamber. According to this design, a prototype of the thruster will be manufactured. The mentioned thruster has been ...
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In this paper, design and physical configuration of various components of a 10N Monopropellant Hydrazine Thruster focusing on design calculations and optimization of catalytic combustion chamber. According to this design, a prototype of the thruster will be manufactured. The mentioned thruster has been designed as a three-piece modular thruster, including an injection system, catalytic combustion chamber and nozzle. Based on analyzes done for each module, the propulsion characteristics of monopropellant thruster system have been identified and used for the next module as necessary inputs. The combustion chamber dimensions are selected based on criterion of maximum decomposition of 40% ammonia and Mach number of 0.02. Also, the third module is the nozzle, designed as a simple cone. The exterior body design of these three modules and their connections to each other, based on considerations of sizing and weight limitation, as well as being dual purpose for use in the cold and hot tests, has been performed.
Hadiseh Karimaei
Volume 11, Issue 3 , December 2018, , Pages 9-19
Abstract
Monopropellant thruster of atitude control system is a requirement for the development and functionalization of satellites in space, which have expensive and high-tech technology. Hydrazine thrusters are currently the most widely used thrusters for guidance and control systems of re-entry and manned ...
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Monopropellant thruster of atitude control system is a requirement for the development and functionalization of satellites in space, which have expensive and high-tech technology. Hydrazine thrusters are currently the most widely used thrusters for guidance and control systems of re-entry and manned spacecraft. In this paper, design and computation of an injector with hollow-cone spray with two tangential inlets as a fuel injector of a 10N monopropellant hydrazine thruster is presented. This injector has designed based on Bazarov method so that can generate a spray with a common (not so big) spray angle and very thin liquid sheet. Therefore it will be suitable from aspect of limitation of the catalyst bed length and also gives finer atomization.The phenomenon of creating and developing an air core in the internal flow of these injectors and its simulation is complex due to the existence of two turbulent swirl flows in two different phases, liquid and gas, which have an interface. For this injector, simulation of the internal flow has been performed to predict the output flow characteristics and ensure the formation of the gas core inside it. These characteristics include the spray cone angle, liquid sheet thickness, the output velocity distribution of the injector nozzle, and etc. For this purpose, volume of fluid (VOF) method has been used and flow turbulence has been simulated using the k-emodel. The results of this study is presented in detail in the paper.
Hadiseh Karimaei; Mostafa Hossein Alipour; F Ommi; Ehsan Movahednejad; Reza Sharifzadeh
Volume 10, Issue 4 , March 2018, , Pages 1-7
Abstract
A swirl injector is tested to investigate the instability of the liquid sheet emanating from it and determine the main microscopic characteristics of the spray. The injector, which is tested, was already approved by doing the characterization tests (macroscopic). Due to the fact that the PDPA systems ...
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A swirl injector is tested to investigate the instability of the liquid sheet emanating from it and determine the main microscopic characteristics of the spray. The injector, which is tested, was already approved by doing the characterization tests (macroscopic). Due to the fact that the PDPA systems to measure the spray characteristics are very expensive and high-tech, and therefore inaccessible for us , it is attempted to investigate the specifications and instability of the liquid sheet as much as possible, by photography. The liquid sheet emanating from the injector has perturbations on its surface which originate from inside the injector. Due to the aerodynamic interactions, these perturbations grow and eventually lead to break up the liquid sheet and form the ligaments. The growth of these unstable waves can be observed in the images. Also the breakup length can be measured using the images recorded. Also ligaments in the primary breakup zone and droplets were shown.
Hadiseh Karimaei; seyed mostafa hosseinalipour
Volume 10, Issue 3 , December 2017, , Pages 59-65
Abstract
The droplet formation stage of a spray, which enjoys a great diversity in size and droplet velocity, is predictable through a statistical approach. Since the available methods require experimental data such as mean droplet diameter and mean droplet velocity as inputs to estimate the distribution of the ...
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The droplet formation stage of a spray, which enjoys a great diversity in size and droplet velocity, is predictable through a statistical approach. Since the available methods require experimental data such as mean droplet diameter and mean droplet velocity as inputs to estimate the distribution of the droplets, this study attempts to propose a consistent theoretical model based on the energy conservation equation for the estimation of mean droplet diameter to be used in the predictive models of droplet size distribution, such as maximum entropy model. Therefore, those models can be independent of experimental data. The parameters needed in the model, such as atomization efficiency and the Weber number are provided using a CFD model. Then, a parametric study to evaluate the relationship between the atomization efficiency and spray velocity, and mean droplet diameter is carried out. This new proposed model entitled energy-based model (EBM) can provide a very good prediction of mean droplet diameter in comparison with the available experimental data.
Saeedeh Ya’ghob-nezhad; Seyed Hamed Hashemi Mehne
Volume 9, Issue 1 , May 2016, , Pages 73-89
Abstract
Because of vast applications of Liquid fuel engines in rockets and importance of their functional parameters such as trust, specific impulse and fuel consumption in engine performance, it is needed to be tested in different functional conditions before operation in actual missions. The analysis of test ...
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Because of vast applications of Liquid fuel engines in rockets and importance of their functional parameters such as trust, specific impulse and fuel consumption in engine performance, it is needed to be tested in different functional conditions before operation in actual missions. The analysis of test data used to improve the design, engine troubleshooting and to expand the production program for future rockets. Selecting the suitable injector(s) is the key parameter for improving combustion parameters. With respect to finding the effective ways to analyzing the engine hardware performance without neglecting from their main characteristics, one of the alternatives is doing the hot-fire tests by using a sub scaled engine instead of the full-scale engine. In this research, the design process and manufacturing details of a 300N trust (nominal) micro engine with single swirl Injector is presented. Initial firings using the actual fuel and oxide were not successful. Low fuel flow, low mixing area of the fuel and oxide, and contamination in the self ignition fuel (TR-1) were considered to be the reasons. Overcoming to these problems resulted in successful firing of the subscale engine.
