Space subsystems design: (navigation, control, structure and…)
M. Navabi; P. Zarei
Volume 14, Issue 4 , December 2021, , Pages 77-83
Abstract
The use of four reaction wheels to control the three-axis attitude of the spacecraft, considering its mechanical performance and the possibility of its failure, is a practical solution in the face of a defect in one of the wheels. In this article, the optimal control of the spacecraft, which has four ...
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The use of four reaction wheels to control the three-axis attitude of the spacecraft, considering its mechanical performance and the possibility of its failure, is a practical solution in the face of a defect in one of the wheels. In this article, the optimal control of the spacecraft, which has four reaction wheels, is investigated. Controlling the attitude of a spacecraft with just two reaction wheels is a significant issue that conventional controllers are not able to do. Therefore, the use of nonlinear model-based predictive controller is used to control the attitude of this spacecraft and compared with optimal nonlinear control in a discrete-time comparison, which satisfies the acceptable results.
A. R. Aghalari; M. Iranzad
Volume 6, Issue 1 , April 2013, , Pages 79-91
Abstract
Precision spacecrafts require high levels of pointing stability. Small levels of vibration can cause a significant reduction in image quality. There are many possible disturbance sources on spacecraft (mechanical systems or sensors), but the reaction wheel assembly (RWA) is anticipated to be the largest. ...
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Precision spacecrafts require high levels of pointing stability. Small levels of vibration can cause a significant reduction in image quality. There are many possible disturbance sources on spacecraft (mechanical systems or sensors), but the reaction wheel assembly (RWA) is anticipated to be the largest. Therefore, accurate models of reaction wheel disturbances are necessary to predict their effect on the spacecraft performance and develop methods to control the undesired vibration. In this paper, two types of reaction wheel disturbance models is presented. The first is a steady-state empirical model that was originally created based on a prototype RWA hard-mounted test data. The model assumes that the disturbances consist of discrete harmonics of the wheel speed with amplitudes proportional to the wheel speed squared. Experimental data obtained from RWA designed and manufactured by Aghalari and et al. are used to illustrate the empirical modeling process and provide model validation. The model captures the harmonic disturbances of the wheel quite well, but does not include interactions between the harmonics and the structural modes of the wheel which result in large disturbance amplifications at some wheel speeds. Therefore the second model, a nonlinear analytical model, is created using energy methods to capture the internal flexibilities and fundamental harmonic of an unbalanced wheel. Then the analytical model has been extended to capture all the wheel harmonics as well as the disturbance amplifications that occur due to excitation of the structural wheel modes by the harmonics. Finally experimental data obtained from hard-mounted test of RWA is used to determine the model parameters for both types of models and a comparison between the models and data is presented.
B. Beheshti Boroumand; A. Ghanbarian; Z. Sadeghi Givi; A. Ahmadloo; K. Raissi; M. Bahrami
Volume 1, Issue 1 , September 2008, , Pages 81-86
Abstract
Utilization of the GPS and telemetry systems in sounding rockets are described in this paper. The GPS system is composed of a GPS receiver and its special antennas for this mission. Telemetry system consists of data transmitter, data receiver, and antennas. Each system undergoes some tests to being verified ...
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Utilization of the GPS and telemetry systems in sounding rockets are described in this paper. The GPS system is composed of a GPS receiver and its special antennas for this mission. Telemetry system consists of data transmitter, data receiver, and antennas. Each system undergoes some tests to being verified for accurate performance in flight situation after design and fabrication. These tests are also explained in this paper.
H. Bolandi; A. M. Gheitaghy; B. Ghorbany Vagheii; S. M. Smailzadeh; M. R. Talaee
Volume 5, Issue 1 , April 2012, , Pages 81-90
Abstract
The responsibility of the satellite thermal control system is to maintain equipments temperature in all external environments and under operational modes within an allowable temperature range. The geometric math model of satellite with available relations in references is obtained and certified with ...
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The responsibility of the satellite thermal control system is to maintain equipments temperature in all external environments and under operational modes within an allowable temperature range. The geometric math model of satellite with available relations in references is obtained and certified with Thermal Desktop software. The outputs of geometric math model are external heating rates and radiation interchange factors. In this paper, the electrical simulation method is proposed as a tool for thermal math model of rotating satellite as equipments and structure of satellite are divided into several nodes and each term of thermal balance equation is simulated with equivalent electrical elements (capacitor, resistance, current source and etc.) and obtained circuit is solved fast and easily with HSPICE code. The values of voltage and current in each node are equivalent to temperature and heat flux, respectively. The results are illustrated the low run time with exact temperature responses of electrical simulation method in thermal modeling of satellite. By using the semi active thermal control, the thermal requirements are achieved and the effect of radiator paint is investigated.
Kamal Jahani; Hossein Farajollahi
Volume 7, Issue 4 , January 2015, , Pages 81-91
Abstract
During launching and deploying to orbit, satellites experience vibration loads from launch vehicle especially in longitudinal direction. Even though the aim of the adapter between satellite and launcher is to isolate the satellite from the launcher's dynamic loads, however, still enough harsh vibration ...
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During launching and deploying to orbit, satellites experience vibration loads from launch vehicle especially in longitudinal direction. Even though the aim of the adapter between satellite and launcher is to isolate the satellite from the launcher's dynamic loads, however, still enough harsh vibration loads that can affect the operation of satellite's delicate systems transmit to the structure of the satellite. Therefore, there is need to isolate the delicate systems from vibrations of the satellite's structure. In this paper, the performance of a new material namely Silicone Gel in isolating delicate equipments (such as electronic board and its components) of satellite from longitudinal vibrations is investigated using finite element method. The results of modeling of an isolator containing Silicone Gel are verified by the available experimental results from the literature. Besides having frequency dependent behavior and dissipation characteristic, Silicone Gel shows hyper-elastic behavior that these characteristic are considered in modeling and analysis. Also an electronic board that overlays on Silicon Gel type mounts is modeled and the amount of transmitted vibration to lead wire of a resistor on it is investigated. The obtained results show that the Silicone Gel has good performance in isolating of delicate equipments of satellite from incoming longitudinal vibrations.Â
GPS and navigation GPS)، GLONASS، GALILEO
Reza Ghasrizadeh; Amirali Nikkhah
Volume 13, Issue 4 , December 2020, , Pages 81-90
Abstract
This paper presents a new approach to eliminating noise and disturbances in the corse alignment process for inertial navigation systemsBecause of extreme fluctuations and quasi-static environments, the corse alignment process often involves a lot of errors and noise. Initially, the coarse alignment process ...
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This paper presents a new approach to eliminating noise and disturbances in the corse alignment process for inertial navigation systemsBecause of extreme fluctuations and quasi-static environments, the corse alignment process often involves a lot of errors and noise. Initially, the coarse alignment process for inertial navigation systems is described exhaustively and then, with the assumption of disturbances and noise, we attempt to nudify to improve and initialize the initialization accuracy. Subsequently, introducing the filtering characteristics of the digital filter for the mutation , Due to the deletion of some of the sensor's main data, identifies the missing parameters and estimates the state variables using the Kalman filter matrix based on the variance of the data error. Identifying the missing parameters of the transformation matrix in the coordinate system using the Kalman filter Matrix is the innovation of this paper, which leads to improved note coarse alignment will be inertial navigation systems.
H. Sedaghat; A. R. Toloei; H. Ghanbarpoor
Volume 4, Issue 2 , January 2012, , Pages 83-92
Abstract
A current method by which star trackers identify stars is to match the angles between stars within its field of view to angles stored in a catalog. If an angle can be matched to one pair of stars, the attitude of the star tracker can be determined. However, the measurement of the angle will include error, ...
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A current method by which star trackers identify stars is to match the angles between stars within its field of view to angles stored in a catalog. If an angle can be matched to one pair of stars, the attitude of the star tracker can be determined. However, the measurement of the angle will include error, and so the true angle can only be known to lie within a certain measured range. The result is, after comparing the measured angle to the catalog of angles, more than one pair of stars can be the correct solution. A method for narrowing down to one solution involves employing many angles within the field of view in a certain order, called “pivoting,” which can be time consuming and does not always yield a solution. another method presented here matches planar triangles made from sets of three stars within the field of view to planar triangles stored within a catalog. By using both the area and polar moment properties of the planar triangle, the range of possible solutions is very quickly narrowed, fewer pivots to other planar triangles are required, and the method is more likely to yield the correct solution than the angle method. New method presented here use these two methods simultaneously, first, by angle method candidate some stars to identification. In this level reduces stars in FOV. Second, by triangle method in fewer time identification completed, because FOV is smaller. So this new method is faster than triangle and more accurate than angle method and we do not pivoting the same as each method. In addition, Simulation results show the performance of the new method as well as its robustness with respect to including false stars.
Space systems design (spacecraft, satellites, space stations and their equipment)
Meghdad Payan; Hanif Kazerooni
Volume 13, Issue 1 , March 2020, , Pages 83-98
Abstract
The need to stay in space and use its advantage in different perspectives, has led our country to take steps to use satellite technology. In this regard, constructing an advanced satellite launch site with all the modern facilities is one of the key issues. Imam Khomeini Space Center is the first permanent ...
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The need to stay in space and use its advantage in different perspectives, has led our country to take steps to use satellite technology. In this regard, constructing an advanced satellite launch site with all the modern facilities is one of the key issues. Imam Khomeini Space Center is the first permanent launch platform of the Islamic Republic of Iran. In 1389, it was announced that due to existing geographic constraints, research was conducted to build the second space center in Chabahar. In this paper, using several performed studies on the infrastructure of the advanced space centers around the world as well as various simulation methods, a conceptual design for the Chabahar launch site is presented. Full descriptions of the launch platforms, processing complex, assembling of satellites, etc. are illustrated. The design and construction of the Chabahar launch site will be a major step forward in the development of the space industry of Islamic Republic of Iran.
B. Shahgoli; P. Moallem; M. KavoshTehrani; Sh. ParvinJahromi; S. A. Hosseini
Volume 7, Issue 2 , July 2014, , Pages 85-92
Abstract
Gyrocompass is used to justify and aim (orient) the missiles; it is used in equipment and accuracy of launch position as well to find azimuth in particular points. Observations and reading in this kind of compass are done optically which suffers from low accuracy and optical illusion. In this paper a ...
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Gyrocompass is used to justify and aim (orient) the missiles; it is used in equipment and accuracy of launch position as well to find azimuth in particular points. Observations and reading in this kind of compass are done optically which suffers from low accuracy and optical illusion. In this paper a simple algorithm is suggested by utilizing methods based on processing digital image and neural networks for automatic reading of a trade gyrocompass. In the method at first, by analyzing the difference of sequential images taken from the compass display, the back frame is specified. Then the display region is extracted by edge detection and morphology operation. After that the segmented numbers are recognized one by one through the trained neural networks. Finally, the gyrocompass angle is calculated accompanied by accuracy of arc second by geometric analysis of relative position of scaled board and indicated index. The usage of suggested method in the step of back frame recognition has been evaluated on 6 real test video sequences and the next steps have also been evaluated on more than 300 real images.
Malihe Hashemi; Seyed Kamaleddin Mosavi Mashhadi; Seyed Majid Esmaeilzadeh; Mohammad Fiuzy
Volume 9, Issue 2 , September 2016, , Pages 85-90
Abstract
Attitude Determining is one of the major and critical satellites space missions. In this study, a new method to Attitude determination of satellites is presented. Such that, based on the proposed method search space will be more limited then accuracy and speed of attitude determination in the proposed ...
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Attitude Determining is one of the major and critical satellites space missions. In this study, a new method to Attitude determination of satellites is presented. Such that, based on the proposed method search space will be more limited then accuracy and speed of attitude determination in the proposed method has risen. At first in this method, implementation and the test algorithms will be discussed, after these some algorithms, such as navigation, pattern recognition and ultimately attitude determination will be reviewed. In order to implement these algorithm. High quality images of stars which must provided by the star tracker camera requires to implement. Really these images to perform the necessary processing sent to the processor so the processor based on designed algorithms, determines the attitude of camera and satellite in all three axes. This means that some features considered for star tracker and based on them begins the designing process. The range of accurately determination for star tracker is one of these features. In this article, the ranges of two axes of Yao and Pitch less than 20 seconds on the scale of degree are considered and in the roll axis less than 100 seconds is intended. Can show in the results, much better accuracy and less than initial assumptions have been achieved. It also carried out by an adaptive identified algorithm so that the brighter stars are identified and based on their attitude determination, the sensor accuracy have increased. Because of according research, the clearer stars, have more accurate in calculation. The other important feature is the speed of attitude detection which performed by 1 GHz processor, and correct identification of pyramidal algorithm where have reached less than 15 milliseconds. Due to the duration, the desire update rate gained. Other important parameters which influence the accuracy of the attitude determination is knowing the exact coordinates of the intersection point vector of focal length lens with image sensors. By Land calibration for camera with a good accuracy, these parameters were estimated.
recognition, evaluation, and detection of space radiation
Marjan Moghanipoor; Maryam Kiani; S. Hossein Pourtakdost; Amir Labibian
Volume 12, Issue 4 , December 2019, , Pages 91-102
Abstract
Temperature sensors have recently been proposed for attitude estimation (AE) of Low-Earth satellites. However, since half of the satellite surfaces do not receive any heat flux from the Sun, conduction occurs among the satellite surfaces. In this regard, the present study has focused on the effect of ...
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Temperature sensors have recently been proposed for attitude estimation (AE) of Low-Earth satellites. However, since half of the satellite surfaces do not receive any heat flux from the Sun, conduction occurs among the satellite surfaces. In this regard, the present study has focused on the effect of surfaces’ conduction as well as inner radiation on AE using temperature sensors. The nonlinear filter of Unsceted Kalman filter is adopted for AE, and the developed model to describe temperature rates is verified using Thermal Desktop and SINDA software. Monte Carlo simulations prove positive effect of the conduction on AE performance against negative role of the inner radiation.
Remote sensing
S. Andishe Moezzi; Mohamad Ali Masnadi-Shirazi
Volume 14, Issue 3 , September 2021, , Pages 91-100
Abstract
synthetic aperture radar (SAR) for ground moving target indication (GMTI) and imaging (GMTIm) have been gaining increasing interests for both civilian and military applications. Because SAR is generally designed for imaging a stationary scene, the SAR image of a moving target will be both displaced and ...
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synthetic aperture radar (SAR) for ground moving target indication (GMTI) and imaging (GMTIm) have been gaining increasing interests for both civilian and military applications. Because SAR is generally designed for imaging a stationary scene, the SAR image of a moving target will be both displaced and smeared.More specifically, by exploiting the inherent sparsity of the moving targets in the clutter-suppressed SAR image domain, in this article. the intended SAR-GMTIm problem is solve by a sparse Bayesian perspective.The theory of CS has been successfully applied to SAR/ISAR imagery to achieve high cross-range resolution with a limited number of pulsesIn order to evaluate the quality of images, we apply the target-to-clutter ratio (TCR), which is commonly used in syntheticaperture radar (SAR) image assessment.The proposed algorithm shows a 10-dB higher TCR compared to the conventional algorithm.
commerce, management, and apace law
Hamid Kazemi; Samaneh Elahian
Volume 15, Issue 2 , June 2022, , Pages 93-102
Abstract
In this article collision probability method is used to satellite collision risk analysis. Among different methods introduced for determining collision probability, Patera's (2005) and Chan methods are chosen to define Noor satellite collision to the other space objects. According to criteria described ...
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In this article collision probability method is used to satellite collision risk analysis. Among different methods introduced for determining collision probability, Patera's (2005) and Chan methods are chosen to define Noor satellite collision to the other space objects. According to criteria described in the article, Advanced Conjunction Analysis Tools of STK software applied for collision risk analysis. The software, determine position of each object in space using Two Line Elements and appropriate propagation model according to altitude of the orbit. So collision probability calculated by one of the cpllision probability methods. If derived prababilty is larger than 10-3, so its necessary to schdule for suitable maneuver to avoid collision.
Space systems design (spacecraft, satellites, space stations and their equipment)
Omid Shekoofa; Farhad Bagheroskouei; Reza Amjadifard
Volume 15, Issue 3 , September 2022, , Pages 93-108
Abstract
In this paper, the feasibility and performance of using solar arrays equipped with sun concentrators, along with other conventional solar array structures, in CubeSats, is investigated for the first time. For this purpose, seven different structures of solar arrays have been defined and implemented for ...
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In this paper, the feasibility and performance of using solar arrays equipped with sun concentrators, along with other conventional solar array structures, in CubeSats, is investigated for the first time. For this purpose, seven different structures of solar arrays have been defined and implemented for more than 24 different CubeSat configurations from 0.25U to 27U. Then, by calculating important system-level parameters such as power generation density, power generation cost, reliability of solar arrays, and also a newly proposed parameter, called shape fit factor, the performance of these structures for the introduced configurations are evaluated and compared. To this end, and by considering rational coefficients, a cost function consisting of the four above-mentioned parameters is defined as the degree of merit of different solar array structures used in each CubeSat configuration. The results show that alongside the use of deployable solar arrays, using concentrating solar arrays can provide new capabilities for CubeSats to overcome the challenge of generating sufficient power.
physiology and space medicine (astrobiology)
Maryam Salavatifar; Nilofar Mosallaei; Ali Hatef Salmanian
Volume 15, Issue 4 , December 2022, , Pages 97-106
Abstract
Gravity is an influential force on living organisms on earth, including microorganisms. E. coli O157: H7 causes complications such as bloody diarrhea and hemolytic uremic syndrome in humans and immunization is the main way to fight it. Subunit B of Shiga-like toxin type 2 (STX2B), binding agent of bacterial ...
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Gravity is an influential force on living organisms on earth, including microorganisms. E. coli O157: H7 causes complications such as bloody diarrhea and hemolytic uremic syndrome in humans and immunization is the main way to fight it. Subunit B of Shiga-like toxin type 2 (STX2B), binding agent of bacterial toxin to target cells, is a candidate for the recombinant vaccine to prevent disease. Due to the quantitative and qualitative increase in the expression of some recombinant proteins under microgravity, the STX2B recombinant protein expression was examined under simulated microgravity conditions on clinostat device. After confirmation of the recombinant by immunological methods, its expression was performed under microgravity and after the protein purification by chromatographic column, its amount was measured. The results showed that despite the decrease in expression under microgravity, which was probably due to lack of proper aeration of the culture medium, recombinant protein was still produced under microgravity condition.
commerce, management, and apace law
Saeed Habiba; Hamid Kazemi; Milad Sadeghi
Volume 15, Issue 1 , March 2022, , Pages 107-119
Abstract
From the past, space activities which has been extremely important for governments as the main and traditional players in the space industry, are now attractive to non-governmental and private individuals, who are the new actors in the space industry. Undoubtedly, in this field, technology is a prerequisite ...
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From the past, space activities which has been extremely important for governments as the main and traditional players in the space industry, are now attractive to non-governmental and private individuals, who are the new actors in the space industry. Undoubtedly, in this field, technology is a prerequisite for implementation and development of space activities. Developing and less developed governments are trying to pave the way for these activities by passing national space legislations, but it should be noted that there are still many obstacles in this way. One of these obstacles is existence of restrictive acts and regulations of developed countries on transfer of technology in space industry. Identifying dimensions of these barriers and limitations and evaluating them from the standpoint of intellectual property rights is the subject of this article. The conflict between tendency towards commercialization of space activities and tight control over technology transfer in the space industry is one of the results that this article has achieved.
A. A. Jafari; A. Mozafari; M. Maghsoudi Mehrabani
Volume 4, Issue 1 , July 2011
Abstract
The effect of rotating speed and stiffeners on vibrations for composite rotors is investigated using Sander's shell theory. The frequency equation is derived implementing the Rayleigh-Ritz procedure based on energy method. The effects of initial hoop tension, centrifugal and Coriolis forces due to the ...
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The effect of rotating speed and stiffeners on vibrations for composite rotors is investigated using Sander's shell theory. The frequency equation is derived implementing the Rayleigh-Ritz procedure based on energy method. The effects of initial hoop tension, centrifugal and Coriolis forces due to the rotation are considered to derive governing equation. The displacement functions satisfying the both ends simply supported boundary conditions are assumed to be trigonometric expressions. By using simple shell theory like as Sander's shell theory the amount of equations and time expenditure are considerably reduced and provides feasible analysis, solution and design especially for composite materials optimization.UD composite materials are used for stiffeners. The effects of these stiffeners are evaluated by an averaging method. Some of stiffeners shapes are considered to optimize the ratio of natural frequency to weight.
Space systems design (spacecraft, satellites, space stations and their equipment)
Hojat Taei; Amirhossain Adami; Mansour Hozuri
Volume 14, Issue 4 , December 2021, , Pages 85-98
Abstract
The need to improve the reliability and safety requirements, has led to increasingly utilization of reliability based design approaches. In this study, reliability based multidisciplinary design optimization for a bipropellant propulsion system has been investigated. The objective function is minimizing ...
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The need to improve the reliability and safety requirements, has led to increasingly utilization of reliability based design approaches. In this study, reliability based multidisciplinary design optimization for a bipropellant propulsion system has been investigated. The objective function is minimizing the total system mass and design constraints are the total impulse and the temperature of the wall of the combustion chamber. Monte Carlo simulation methodology is used to apply uncertainties in the problem and to show the reliability of the system under these uncertainties. The mass, functional and geometric results of the bipropellant propulsion system are differentiated for optimal design, reliability based design and optimal reliability based design. Then, considering the results, the concepts and definitions of design methods are compared and discussed and it is shown that the reliability based multidisciplinary optimization while having the desired mass, has high reliability.
Remote sensing
Fereydon Nobakht Orsi; Abdolreza Safari; Amir Khodabandeh
Volume 14, Issue 3 , September 2021, , Pages 101-108
Abstract
In this paper, we discussed standard point positioning technique based on the single frequency code-based (C/A) receivers. Then, we presented its performance by means of different measures. However, the use of one single frequency GPS receiver to obtain high-precision positioning make a major challenge ...
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In this paper, we discussed standard point positioning technique based on the single frequency code-based (C/A) receivers. Then, we presented its performance by means of different measures. However, the use of one single frequency GPS receiver to obtain high-precision positioning make a major challenge due to the environmental biases, in particular the ionospheric effects are handled. The main objective of the present study is to integrate a inospheric model such as Klobuchar Inospheric Model (KIM) with imprecise code (C/A) observations under intense geomagnetic storm conditions, then, to obtain dm level positioning accuracy using Kalman filter. For this purpose we used code (C/A) observations on two different days (February 26, 2018 and December 20, 2015) at Tehran station. The results show that we could obtain multi-dm level positioning accuracy under geomagnetic storm condition by using Kalman filter that will be important in the field of kinematic applications.
Space subsystems design: (navigation, control, structure and…)
Fatemeh Asdaghpour; Fatemeh Sadeghikia; Mohammad Ali Farsi
Volume 15, Issue 2 , June 2022, , Pages 103-113
Abstract
Antennas, which are usually installed on the outer shell of these systems, are therefore always exposed to the thermal fluctuations of the space environment. Thermal fluctuations cause the antenna surfaces to expand, contract and distort and can cause the antenna to malfunction. In this paper, the effects ...
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Antennas, which are usually installed on the outer shell of these systems, are therefore always exposed to the thermal fluctuations of the space environment. Thermal fluctuations cause the antenna surfaces to expand, contract and distort and can cause the antenna to malfunction. In this paper, the effects of thermal expansion and contraction due to an LEO orbital mission on the radial characteristics of two X-band reflective antennas, one broadband antenna and the other narrowband, And the resulting radiation characteristics are compared with the characteristics of equivalent sample antennas at ambient temperature. Analyses show that narrowband antennas are very vulnerable to thermal fluctuations and, therefore, it is necessary to choose the material of the antennas from materials whose thermal expansion coefficient is very small. In addition, choosing the appropriate protection method to maintain the optimal performance of the antenna is one of the most essential activities in the construction of space antennas.
Space systems design (spacecraft, satellites, space stations and their equipment)
Amirhamzeh Farajollahi; Reza Firuzi; Mohammad Reza Salimi; Mohsen Rostami
Volume 15, Issue 4 , December 2022, , Pages 107-121
Abstract
In this study, the effects of geometry and spiral rifling like guides inside the injection nozzle on the performance of an engine are investigated, using AVL Fire software. To do so, firstly injectors with different nozzle geometries and their resultant spray patterns were simulated. Numerical results ...
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In this study, the effects of geometry and spiral rifling like guides inside the injection nozzle on the performance of an engine are investigated, using AVL Fire software. To do so, firstly injectors with different nozzle geometries and their resultant spray patterns were simulated. Numerical results of this step show that creation of spiral rifling like guides inside the nozzle increases the spray cone angle and improves fuel atomization quality. In the next step, effects of using forgoing nozzle geometries on sample engine characteristics were studied and the related results compared to those of common cylindrical injectors. Numerical results of this step clearly show the superior performance of nozzles with spiral rifling like guides. In this case, SFC reduces up to 32 percent while the engine power and it's torque rises more than 63 percent. Also the amount of pollutants like NOx reduces 12 percent with respect to common cylindrical nozzles.
Space systems design (spacecraft, satellites, space stations and their equipment)
Sajad Davari; Hadiseh Karimaei
Volume 15, Issue 3 , September 2022, , Pages 109-118
Abstract
In this research, design and simulation of a single capillary injector and three-hole circular injector plate of a 10N Hydrazine monopropellant thruster were performed. Ansys Fluent software was used to simulate the injector and injector plate . Volume of fluid (VOF) method was used to simulate such ...
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In this research, design and simulation of a single capillary injector and three-hole circular injector plate of a 10N Hydrazine monopropellant thruster were performed. Ansys Fluent software was used to simulate the injector and injector plate . Volume of fluid (VOF) method was used to simulate such a flow and turbulence was simulated by k-e model. The characteristics of the injector and injector plate including mass flow rate and average velocity in the injector nozzle were calculated by changing the inlet pressure. The results showed that the injector and the injector plate have the ability to supply the desired mass flow rate of the monopropellant thruster at a known design pressure. In fact the capillary injector has replaced swirl injector with hollow cone spray used in the previous version of this thruster. The dimension of the chamber was significantly reduced by using the capillary injector, which reduces both the volume of the expensive iridium catalyst and weight of the thruster.
Space systems design (spacecraft, satellites, space stations and their equipment)
Hanieh Eshaghnia; Mehran Nosratollahi; Amirhossain Adami; Hadi Dastoury
Volume 15, Issue 1 , March 2022, , Pages 121-137
Abstract
Turbopump propulsion systems have been used in almost all launch vehicles. With the advancement of manufacturing technologies, especially in the use of composite and lightweight structures, the use of non-turbopump propulsion systems has been considered due to the reduction of operating costs. This study ...
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Turbopump propulsion systems have been used in almost all launch vehicles. With the advancement of manufacturing technologies, especially in the use of composite and lightweight structures, the use of non-turbopump propulsion systems has been considered due to the reduction of operating costs. This study has been investigated the multi-disciplinary optimization design of a two-stage launch vehicle using a pressure-fed propulsion system for both stages. Two main propulsion systems including gas-pressure and self-pressure feeding systems, have been evaluated in different configurations on two launcher stages. To extracting the optimum and possible solution, the launcher mission also has been added as a design variable in the optimization algorithm. The launcher has been extracted and introduced for each specific configuration of the launcher to achieve a certain orbital altitude with the maximum carrying payload and minimum gross mass. For this purpose, the AAO multidisciplinary optimization design framework has been used. The system-level and subsystem optimizer of the GA-SQP algorithm have been chosen.
Space systems design (spacecraft, satellites, space stations and their equipment)
Masoud EidiAttarZade; Atiyeh SarAbadani; Ghazal Davarnia; Hamed Khosrobeygi; Mohammad Farshchi; Alireza Ramezani
Volume 14, Issue 2 , June 2021, , Pages 47-37
Abstract
Numerical modeling of space engines aside the experimental test is routine. In the design step of such engines, low-cost softwares are vital. In this paper, small-scale space engine thrust chamber analysis code will be developed. In this code, propellant injection and evaporation distribution will be ...
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Numerical modeling of space engines aside the experimental test is routine. In the design step of such engines, low-cost softwares are vital. In this paper, small-scale space engine thrust chamber analysis code will be developed. In this code, propellant injection and evaporation distribution will be modelled. 1D Combustion solver calculates the reactions of distributed fuel and oxidizer through the thrust chamber axis by chemical mechanisms. Then the cooling solver computes the heat transfer from hot gases to the film cooling layer and the outer surroundings. Validation shows acceptable errors in the modelling of processes. By this developed code, the performance of the Astrium bi-propellant thruster with MonoMethylHydrazine and NitrogenTetrOxide and distributed chemical reaction has been investigated. Results show that hot gas temperature inside the combustor is not uniform and has a peak. Furthermore, the evaporation of the propellant droplets is continued to the nozzle throat.
GPS and navigation GPS)، GLONASS، GALILEO
MohammadAli Amiri Atashgah; Seyyed Mohammad-Jafar Tabib
Volume 14, Issue 2 , June 2021, , Pages 49-59
Abstract
This research represents localization of an aerial robot using fisheye cameras on walls in a simulation environment. The virtual testbed in this work is a quadrotor that is simulated in MATLAB Simulink. Subsequently, the simulation outputs as flight records are used in a virtual lab, which is developed ...
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This research represents localization of an aerial robot using fisheye cameras on walls in a simulation environment. The virtual testbed in this work is a quadrotor that is simulated in MATLAB Simulink. Subsequently, the simulation outputs as flight records are used in a virtual lab, which is developed in 3DsMAX. Then, the virtual fisheye cameras (here two) are installed in some different points on the walls and the related images from the cameras are received offline. The gathered images will be processed by OpenCV in a C++ environment. For external calibration, each fisheye camera takes an image from a known pattern consist of some lights placed in the virtual lab. We execute Perspective-n-Point method on the images to obtain pierce direction/position of the camera. For more, the aerial robot is localized by computing the nearest point between two lines of sight. In brief, the outcomes exhibit an accuracy of 4cm in the center of the virtual-room room.
